i can't offer advice as such- but i can tell you you are not alone.

when i was at colledge (or at least the early days of colledge) i did the same as you- i'd just come back from classes (which usually i totally failed at) and then just eat... sometimes for like 2 hours at a time- comfort eating

i had my own room in this .. what the colledge called hostalls- so i usually ended up being ill in my own private sink- and then for the rest of the evening, doing the best to hide the fact it was me... i'd go somewhere else- and if people asked about it, i'd just say i didon't have a clue where it came from

sorry- i know it's not much help. but i hope at least it's comforting knowing you arn't alone