LIBRA GIRL NURSE
Losing and gaining real and false friends hasn't actually got anything to do with your chest size, it's aobut how you feel about your body. So, what you need to do is work on being you, only you, and getting to love the skin you're in, with all the good bits and bad bits. This is the only way you'll be able to find long term friends, when you're happy within yourself. No one says that this is easy, but its a day by day thing that will stand you in good stead for the rest of your life. Talk to mum about making sure that you're wearing the best supporting bra so that you can feel at your most confident, and if you feel that you're a bit over weight, then start to keep a food and exercise diary so that you can work out the times when you fall down in what you eat and do. It's fine to have the occasional treat, but overall you should have a well balance diet. Perhaps you and mum could work out a plan together.
As for the guys calling you meth, they think they're really original and funny. It might be annoying, but it's totally normal for them to behave like this. If you want them to stop, ignore them. Don't give them any reaction at all when they say it, and definitely don't answer to it. Over time it will become really boring for them, you just have to wait them out