I wouldn't worry about it.  Nothing sounds gluttonous about what you describe.  Evidently you have a robust metabolism and the food does not put extra weight on you (describing yourself as underweight makes it sound as though you could actually afford to eat a bit more).

We have to keep our health up.  Everyone has different needs regarding food intake.

If you are eating because you are hungry and stopping when you feel full, that’s not gluttony. Actually, some people need to eat in this manner, many smaller meals throughout the day instead of the standard American three meals, breakfast, lunch, and dinner, dinner being the largest meal before bedtime. It’s generally better to eat one’s main meal midday for in the morning than close to bedtime. It’s the way the economic and educational systems in the US are set up that have come to dictate when and how much one eats. 
Gluttony would be continuing to eat even after full, for the pleasure of eating. If done somewhat, not regularly it is a venial sin. If it is habitual, to the point of becoming physically ill, or of eating a peculiar, unhealthy, or in a compulsive manner,nit is probably a mortal sin.  

If you are eating because you are hungry and stopping when you feel full, that’s not gluttony. Actually, some people need to eat in this manner, many smaller meals throughout the day instead of the standard American three meals, breakfast, lunch, and dinner, dinner being the largest meal before bedtime. It’s generally better to eat one’s main meal midday for in the morning than close to bedtime. It’s the way the economic and educational systems in the US are set up that have come to dictate when and how much one eats.
Gluttony would be continuing to eat even after full, for the pleasure of eating. If done somewhat, not regularly it is a venial sin. If it is habitual, to the point of becoming physically ill, or of eating a peculiar, unhealthy, or in a compulsive manner,nit is probably a mortal sin. 

In some subcultures within the United States, such as in rural areas, lunch (sometimes called "dinner") is the big meal of the day, and the evening meal is just a light supper.

I find these days that I often do not want much to eat for the evening meal.  I was traveling out of town this afternoon, and even though I had had a moderately-sized noonday meal, towards the end of the afternoon, I was hungry again, and stopped at Culver's for a small hamburger (just the burger, no fries, and a soft drink I had in my car cooler).  When I got home this evening, all I wanted for the evening meal was a couple of slices of buttered toast and a glass of chocolate milk.

As I said upthread, different people have different needs in this regard.

Yep that sounds like how it was in my grandmothers home in Wisconsin A hearty lunch and then a super light meal in the evening often paired with something like whole milk. I really love the vibe of the midwest man. I still haven't tried Culvers yet though...             

On my commute home I was listening to a homily from Fr. Novak of the FSSPX and he recommends to deny ourselves our favorite foods once in a while to subdue our passions. This could work with anything though. Friends we enjoy talking to, movies we like, books, etc. We can't have too much earthly attachment to things that give us pleasure here because most of our attention ought to be towards God. God bless you brother and thank you for replying

If you have a Wisconsin connection, you have no excuse for not trying Culver's

For the uninitiated, Culver's is kind of like what Chick-fil-A would be, if they served hamburgers instead of chicken.

Their livery is in various shades of blue, very unusual for a fast-food restaurant, when you stop and think about it.  Most such restaurants have various shades of red, orange, yellow, and so on.  Probably has something to do with getting the customers excited and thinking in terms of something to eat.

When I lived with the Amish in the 1980’s, dinner, the main meal, was the largest and main meal of the day.  That was somewhat true even of the school children. They carried “dinner pails” to school with lots of food. In winter, there would always be a hot main dish cooked in the heating stove, like hearty soup or stew. Children would bring food wrapped in foil to place on the stove. By “dinner break” it was cooked, and the school always smelled delicious in cold weather!  Dinner was a full hour and a quarter, lots of time to eat, socialize, play afterwards, or even lie down in the attic on the matting with a shawl for a nap. 
Breakfast would be hearty, but not huge. Usual was oatmeal or fried corn mush, fried eggs, sausage or scrapple, bread, butter, milk, maple syrup or molasses for sweetener, coffee for the older folks. After evening chores was supper, the lightest meal of the day. It’d be milk soup maybe with a can of corn, diced potato, or peas cooked in, basic milk soup was milk, butter, salt, pepper, and a bit of corn starch or leftover mashed potato, corn mush, croutons or bread in some form. A glass of water or herbal tea. That’s it, because once the dishes were made away, everyone went to the living room for the Bible readings, night prayers, followed by bedtime around 8:00, or 9:00 in summer.  The adults and older teens got up early, about 4:00 AM to milk the cows, Mom about 4:30 to pack school dinners, start breakfast, make preparation for the day’s work, followed by the scholars around 5:00 to do their chores, gather eggs, feed cows and horses, make beds, help in the kitchen like set the breakfast table, change the baby’s diaper, get the little ones up, hands and faces washed, dressed, about 5:30, 6:00 was morning prayers followed by breakfast, scholars would wash up, change to school clothes, head out for school by 7:00. School took up at precisely 8:00. Those who weren’t seated and ready to work at 8:00 were tardy. Depending upon the weather, more or less time was needed to walk to school. 
It was a totally different lifestyle and the eating schedule suited it. 

When I lived with the Amish in the 1980’s, dinner, the main meal, was the largest and main meal of the day.  That was somewhat true even of the school children. They carried “dinner pails” to school with lots of food. In winter, there would always be a hot main dish cooked in the heating stove, like hearty soup or stew. Children would bring food wrapped in foil to place on the stove. By “dinner break” it was cooked, and the school always smelled delicious in cold weather!  Dinner was a full hour and a quarter, lots of time to eat, socialize, play afterwards, or even lie down in the attic on the matting with a shawl for a nap.
Breakfast would be hearty, but not huge. Usual was oatmeal or fried corn mush, fried eggs, sausage or scrapple, bread, butter, milk, maple syrup or molasses for sweetener, coffee for the older folks. After evening chores was supper, the lightest meal of the day. It’d be milk soup maybe with a can of corn, diced potato, or peas cooked in, basic milk soup was milk, butter, salt, pepper, and a bit of corn starch or leftover mashed potato, corn mush, croutons or bread in some form. A glass of water or herbal tea. That’s it, because once the dishes were made away, everyone went to the living room for the Bible readings, night prayers, followed by bedtime around 8:00, or 9:00 in summer.  The adults and older teens got up early, about 4:00 AM to milk the cows, Mom about 4:30 to pack school dinners, start breakfast, make preparation for the day’s work, followed by the scholars around 5:00 to do their chores, gather eggs, feed cows and horses, make beds, help in the kitchen like set the breakfast table, change the baby’s diaper, get the little ones up, hands and faces washed, dressed, about 5:30, 6:00 was morning prayers followed by breakfast, scholars would wash up, change to school clothes, head out for school by 7:00. School took up at precisely 8:00. Those who weren’t seated and ready to work at 8:00 were tardy. Depending upon the weather, more or less time was needed to walk to school.
It was a totally different lifestyle and the eating schedule suited it.

How did the Amish feel about you being a Catholic?