Even though the OP's BB is now back together, a few things are worth mentioning for completeness.
Remember, the fixed cup threads are left-handed unless they are traditional French or Italian.
ppg said
Just tighten the drive-side cup all the way and then back it ever so slightly
I suspect he meant the non-DS. The fixed cup on the DS must be tight (
really tight for French or Italian) and adjustments are made on the left side. The idea behind "backing it off" is really that getting it spot-on can be iterative. You set the adjustable cup then tighten the lock ring without moving the cup. In my experience the extra pressure of the lock ring can flex the threads enough to pull the cup
away from the shell a tiny amount. This loosens the bearings, so backing off would be the wrong thing to do. You have to set the cup, tighten the lock ring, then test it, and most likely repeat. When you get it right, walk away...