Hi JB, I might recommend the vaginal ring to you as a new form of birth control to try. I also suffer from nausea and all the unpleasant things (I'm about 100 pounds, so low weight also!) and I've tried probably 5 or 6 different types of birth control (patch and various pills) and have settled on a generic form of Yaz for a variety of reasons. However, I have a friend who has tried the NuvaRing and she is very happy with it. But I'm not a doctor and I'm not a birth control expert, just a content user!
My advice to you may be to watch what you eat before and after you take an oral contraceptive, especially if you have an irritable stomach. Avoid citrus and acidic foods that can cause increased side effects. If you plan on having children in the future, perhaps something like an IUD.
The great benefit of birth control is that for women whose hormones are naturally "out of whack," it can regulate that. In addition to seeing your OB/GYN, I think you may benefit from seeing a hormone specialist to see if perhaps there is something he/she may be able to help you with without turning to contraceptives.