Quit the pill?

I've been on birth control in the form of the pill for a little over a year. I got on it when I was 18 to help with menstrual cramps and to make my period lighter; I also got on it because I was sexually active. Now, my boyfriend and I have decided to stop having sex until we are married. Even before we made this choice, we always used condoms in addition to my birth control. Being on the pill for just this one year has resulted in me gaining nearly 40 pounds, and I cannot lose it no matter what I change about my lifestyle. I'm considering dropping the pill since it resulted in so much weight gain and since we're no longer having sex. I'm nervous about it, however, because before I got on it my periods were heavy and my symptoms were very painful (such as awful lower back pain.) Any advice or help would be greatly appreciated!