Weight gain after stopping birth control.?

I am 31 and have been taking birth control for 11 years. I discontinued taking them 1.5 months ago. I have gained 8 pounds since. My weight does not normally fluxuate and I have been approximately the same weight for 2.5 years. I have not changed my diet nor my activity level. I realize I have changed my hormone levels, but I have never gained weight when stopping birth control in the past. How long before my hormones are regulated, and should my weight stabilize and return to normal?