Just hit up a few stores and try on a lot of different swimwear. You'll find something. You're not the only girl in the world with a small chest size. No one will laugh. That's all in your head girl.
What push ups have you tried? There are many different ones you can use Also wear a triangle bikini top (like a halter) and have it as a push up. Not only will it push them up a bit but the triangular effect gives them something of an optical illusion effect to make them look a little bigger. Also remember: How many female celebs go out in bikini's with small boobs?! Jennifer Aniston Kate Hudson Mila Kunis So you see you are not alone and your friends won;t make fun of you :)
try putting in some tissues or smooth surface padding in the bikini but make sure that its not too big because then your friends will find out. since you have two montha you have all the time to test materials