To do it right, you should have ICAT cans (Insulation Contact Air Tight), caulk them to the ceiling, and build sealed boxes to go over them in the attic. Ceilings cans get a bad rap for air leaks. My so-called ICAT cans have plenty of air leaks. If you go up in the attic, you can see light coming through them. I also used LED retrofit units for lights, which save a lot of electricity, and are a further sealing step as they are closed, rather than open.

Even if the cans are sealed, they get warm, particularly with incandescent bulbs. The heat of the can can create a warm spot on the roof, which can lead to freeze/thaw, and ice dams. That's why I put boxes over mine.

Have you considered surface mount LED's instead?

I use mastic tape. caulk falls out of gap &/or shrinks. these areas

never get a second pass after the first pass of caulk has dried.

Hardcast brand 1402 mastic tape in small manageable pieces

to seal from ceiling into the recessed light.

one shot...done. then do remove the supply grills & bath fan

cover seal those oversized gaps.

over the years I've tried many methods, this is the one

that makes a long lasting seal. can't do better than this IMO

& testing.

best of luck.

Thank you both for your suggestions. This will help me.