If you believe that the enemies of the Church are as St. Pope Pius x said figuratively "to be beaten with fist", I would avoid receiving sacraments from novus ordo ordained clergyman.  We cannot resist lawful authority unless for serious reasons.  Those who made the new religion in their image and likeness are like Judas, seeking to marry worldly compromise with Jesus Christ.  So as good the intentions that  conservative novus ordites have, they need to fix the doubtful holy orders issued from the modernist.  We have good will for those with the problem but it will be up to them to seek the solution.

So you are saying that FSSP are essentially novus ordo with some Latin sprinkled on?

Ok, I'm just getting some clarity about the origin and evolution of the SSPX thanks to the recent multipart
interview with Bishop Williamson.
If I'm to understand correctly the general consensus here is that the FSSP was an offshoot of the
SSPX but their priests differ in that they were ordained by novus ordo bishops, therefore all the times I've been to
confession and communion at an FSSP church has been for naught?

Well, you can't really say that with certainty, anymore than you can say the opposite with certainty. This is due to there being good reason to doubt the validity of perhaps all NO ordinations, but perhaps not all NO ordinations. This is the reason why +ABL wanted Rome to guarantee that they would supply his SSPX with their own bishops - so as to remove all doubt.

Bishop Williamson's explanation on validity is coherent.  My issue with many of the controversies is when Archbishop Lefebvre's opinion is always the final truth.  It seems presumptuous and clingy to not argue the Church Fathers, or encyclicals, or Tradition.  As faithful a servant the Archbishop was, he wasn't the only cleric that was faithful to the Church.

Mmmm....

It's hard to imagine going to hell on a technicality (particularly in the crisis in the Church today), since that would seem to contradict God's perfect justice and charity. 

If even the best theologians in Tradition (Msgr. Williamson mentions Abbe Pierre-Marie of the Avrille Dominicains and Abbe Calderon of the FSSPX) can only arrive at a "probable" answer, than what are men like you and I to do?

Only my opinion, but I can see God judging us by the lights and graces He gives us, and the degree to which, once they are known to us, we cooperate or oppose their effecaciousness.

Are 9 year-old boys expected to successfully wrestle -and correctly resolve- issues the theologians are divided on, or on matters in which they can only arrive at probable conclusions?  Because their parents took him to a chapel with only probably valid priests?  Or does invincible ignorance mitigate culpability?  Almost certainly, to one degree or another.  If not, protestant predestination would rule, since such people would never have had a chance to save their souls (which is against the Faith).

In your case, you are in the beginning stages of learning there is a dispute and a doubt/controversy (perhaps minor, but a doubt nonetheless).  Instead of worrying about your past sacraments, consider what you must do to remove yourself from the doubt: Receive the sacraments of a priest about whom there is no doubt. 

Perhaps that is why God has introduced you to this doubt (i.e., it is a grace, although it feels like an uncomfortable perplexity)?

Every time you open a book, or read an article to learn the truth, it is an implicit act of love of God (in fact it is the spirituality of the Dominicains to "find God in the books").  The hunt for truth is a cooperation with (actual) grace, and it pleases God to see you race to obtain Him.  When you move toward Him, He moved toward you.  That's an encouraging and consoling thought.

If you should die 5 minutes before you find your answer, if is difficult to believe God damns you, presuming you did your part, an were found fighting.

I think after some more time, reflection, counsel, and prayer (this doesn't usually all happen in a day, and certainly not from reading a few internt posts) you will arrive at a peaceful and tranquil conviction that receiving certainly valid sacraments from certainly valid priests is a no-lose proposition.

If you are hung up on the legal aspect/scruples regarding ordinary jurisdiction, the FSSPX would be a place for you to park and study for a while.  They have their issues, but certainly valid sacraments and jurisdiction are not among them. 

I'm sure some here will have issues with what I said above, here or there, but I'm just talking to you personally, and telling you what I think.  It may not be impeccable advice.