when you're told birth control would fix your problems

I had the IUD Mirana for 5 years. Then ONE shot of Depo. Both rely on progesterone 
Since coming off BC in December I have gained 16lbs (even though I am on a strict diet and excersise regularly) 
I now also have acne, insomnia and cramps throughout my cycle. 
Today, the doctor suggested BIRTH CONTROL. I really don't want to gain anymore weight, but I also want to keep trying to convince. They said so long as my cycle is regular (which it is) there is nothing they can do? What should I do?