Good luck, and I hear where you're coming from . I had body issues since about 17 years ago....I don't really have any advice, apart from what the others said, but what I will say is that I found (and this is just me, but it could help you) I lost weight after both bubs, so that each time I have been lighter than before I got pregga's. I wouldn't put this down to breastfeeding, as I stopped that 6 months ago and haven't put on weight since, but I'd say its the running around after bubs, getting up at night, and eating correctly! The BF prob helped at the beginning to get the initial weight off.
So just hang in there, enjoy the pregnancy and spoiling yourself, and know that afterwards you will lose the weight if you eat properly and chase bubs around!!!And I hope you find some support to help you through the pregnancy when you have depressing thoughts about the weight gain. Im sure you'll find alot of help on BB. xoxoxo