I'm so insecure about my body!?

I'm 17 years old and I'm about 106 lbs. I know that doesn't sound like a lot, BUT I'm soooo flat chested. I'm an A. I have absolutly nothing in the front..and I refuse to go swimming in public. I starting taking the depo birth control shot about 5 months ago which is said to make you gain at least 5 lbs a year. And I've already gained about 4 lbs over these past months since I started the shot. My stomach pooch sticks out way farther than my . So I look like a little pregnant girl. I'd feel better if my stomach was smaller than my s. Tips to loose weight, but not in your area? Is that possible? And how to feel more confident in a bikini? I feel like I'm NEVER going to grow any ! :(