i know people who have bad pms and get really bad psych symptoms as well take the pill but skip the sugar pills and don't have a period. some drs recommend you should let yourself have a period every 3months to prevent breakthru bleeding but i don't think it is bad for you not to.

I can imagine that at 15 the thought of going to a gyn might be really scary and embarrassing, it is intimidating for anyone!! but I think it will be really helpful. although a pasychiatrist is a dr, they really only know about their little area of specialty and not so great on other areas. This is really disrupting your life and you are going to have periods for many more years so do everything you can to find a way to help manage it.
With your heavy bleeding and terrible stomach cramps you should also see the dr to check out things like anemia, endometriosis and other gyn probs

Let us know how it goes and hope the gyn helps and isn't too painful.