If I take Maria Regina’s advice regarding the possibility of priests from the 1920s onward being imposters, the last validly 100% sure, validly baptized person in my family was my grandmother, born and baptized 1916.  There is no reasonable means of discovering if the priests who baptized my parents were priests, no way of finding if the priest who baptized me was a priest, no way of investigating the background of every single priest from whom my grandparents, parents, myself were true priests, how many Sacraments were invalid, or if anyone after my grandmother was or is truly Catholic.  

This makes a great case for staying “home alone.”  In fact, all but one person in my extended family stays home alone.  He goes to the novus ordo when his health allows, once every few months, but getting less frequent.  One of the home alone members reads the traditional missal and tries to listen to a sermon from the Sunday following on line.  The remaining members, many, many, scattered to the winds stay home, go out, go shopping, play sports, work, do whatever they want because they were doubtfully baptized but never religious.  The vast majority weren’t baptized and belong to the most common American creed known as, “no religion.”

Please don't give in to negative doubt.  Unless there's a specific reason to doubt a specific priest, they are presumed valid, and theologians all agree that God "will take care of it" in His Providence.  This is NOT a reason for home-alone-ism.

And were the priest to say: "I forgive you your sins in the name of the Father and of the Son and of the Holy Ghost"? Opinion? I would guess valid.