What will yoga and pilates do in my situation?

I am getting a lil pudgy now, I have cellulite and my stomach has that lil ponch going on and I wanted to be toned for this summer. I am not overweight or anything its just i I have eccess fat from the birth control i was put on and i want it tightened and toned. If I did yoga/pilates will this do the trick? I dont want to loose tonnes of weight because my upper half is skinny and i dont want to loose my cup size.

Also how many times a week and for how long should I Do yoga?