As your body adjusts back to a non-pregnant state, you are likely to see many changes. You should consult your OB/GYN for what to expect.
Now, that being said, on to the central part of your question.
Unless it is something your physician prescribed, DON'T DO IT!!!
All those over the counter "miracle" creams, pills and treatments are about 10,000 times more effective at lightening your wallet than they are at producing the promised results.
DON'T WASTE YOUR MONEY!!! If you are breast feeding, some of these things could also actually be harmful to your child!!!
Just like those late night penis enlargement commercials, the stuff doesn't work. If it did, there would be almost nobody out there who wasn't sporting a 12 inch penis or a pair of DD cup breasts. If it sounds too good to be true it most likely isn't true.
Just go talk with your physician and see what she says.
Good luck.