Go talk to a Ob/Gyn about
birth control options. Share your history with her about
your medications and UC. DO NOT LIE about
ANYTHING and ASK TONS OF QUESTIONS--trust me, there is nothing too embarassing.
Just a warning, since it's going to be your first time, sex during a flare hurts. A lot. Don't judge whether you enjoy sex or not based on just one experience with it. Actually... that's good advice for anyone contemplating losing their virginity ;-)