I had a prolactinoma back when I was 21 (now 30) with my prolactin levels in the 300's (no, that's not a typo). I was horribly sick and skyrocketed from 170 to 300lbs (I will admit that my habits were not overly healthy during that time).
After 2 years of medications I was tumor free but have an "empty" space (I forget the term they used) where it was.
Like I said, I don't know if it made my weight gain worse, but I do know how difficult it is to live with a prolactinoma and how hard it is to just get out of bed in the morning.
Positive vibes to all dealing with this.