Why Am I Constantly Bloating?

[Angie.]

I don't normally eat breakfast, usually have a pack of crisps and sandwich for lunch, i don't drink a lot in the day time but over eat near bed time, i'll have dinner then something sweet like cake and i can't stop eating biscuits i can never just have one. By this time, my tummy is totally bloated, someone has actually asked if i was pregnant after eating three small slices of french stick! I get really bloated even after just having a small drink. I don't know what's wrong with me. And by the time i've woken up after sleeping, my tummy's totally flat. I have asthma but try to exercise every few days. I have my prom in about a month and am worried about looking bloated and fat. I'm constantly scared to eat. Please help me :(