Hi Parker, you're on T correct?
I am not a doctor, but i thought the testosterone just kind of slowed down the process until it eventually stopped. So, I think the lining is slowly increasing.
From what I've also heard, women who live together have periods that often sync up (unless of course one has some kind of imbalance) because people who live together often have similar eating and other habits. Food, exercise, etc. can effect your hormone levels, and somehow that can sync you.