When I was birth control the first time, it made my periods lighter and shorter and I had no cramps. A few years after I started, they put me on triliptal, even though they knew I was birth control. Over a year later and two Pdocs later and several different pharmacists, one finally told me that triliptal was making my birth control ineffective for protecting against pregnancy (luckily, I hadn't had sex yet). I was pretty pissed, to say the least. Moral of the story... ask questions of your pdoc, regular doctor, and the pharmacist to make sure you drugs won't interact, and always use backup protection such as condoms.
Another note about birth control... I went off all my drugs (birth control and psych meds) but after a few months went back on birth control. Exact same pill, but completely different results. Sure, my periods are short, I don't have cramps, and less acne, but my period are SO much heavier. When I finish this prescription, I'm going to try a new birth control because I think I'm getting a little anemic.
Just talk to your doctors and maybe try one or two out.
Good luck! Be safe!!

Ro