Alright, attic conversion with drywall, eh? Suddenly I'm back in my grandpa's workshop! Properly insulating a loft is crucial, and it sounds like you're covering all the bases. Thinking back, I helped a friend re-do their garage and the vapour barrier was a NIGHTMARE to seal properly – leaky vapour barrier, mold city! Haha, those were papa's games, but sealing every single little gap in the foil is key; don't underestimate it.