My periods have never been regular. My weight has ranged from normal to overweight and back, so that probably isn't what's affecting it.

If I recall correctly I got tested and have too much testosterone in my body. Not enough to cause any really bizarre effects but enough that they started me on birth control to regulate my periods.

With BC, my periods are fairly regular, without; I won't have them for several months or more.

I am on several psych meds but the one I'm on that effects prolactin is called Invega Sustenna (its related to risperdal) and I have problems with TMI: lactation occasionally and I haven't had my periods.

Soooo to sum my rambling up, I have no clue, there are many factors that could be playing into it so I would advise you to bring it up with your doctor and maybe I should look into it s well because it can't be healthy just not having it? Good luck