Post-partum belly..?

3 years ago when I was 19 I had a unplanned pregnancy and had a closed adoption. Well, my stomach was left with a web of stretch marks and a flabby stomach (not appropriate for bikini weather). Be aware my stomach is flat but needs a lot of work. Has anyone else experienced this?  How can I lose the flab and tone just that area without starving myself? Post a picture if you'd like. Just feel like a old lady because of my stomach I feel like I ruined my body lol. Thanks ladies