Just curious- proofing questions

Hey everyone, I've tried some loaves with minimal success. I've narrowed down my problem (potentially) to my proofing time. typically most of the recipes I've tried state to proof for 2-3 hours, but I'm wondering if that is because they're assuming conditions of 85-95F during proofing time. If you live in a frigid house like me (68F), how long would you proof your roundies? I'm guessing that's the problem, as I've followed multiple recipes to a tee, and all of my loaves have come out flatter than Texas.
Thanks in advance!