I try to eat in 1/2's over the weekend. For ex, for lunch if I have soup and sandwich I only eat 1/2 sandwich and 1/2 my soup then in a few hrs if I'm hungry again I'll finish what's left and I am still consuming the same amount of calories.
Maybe suggest to your friends less food driven get together over the weekend. This is hard because no matter what when you plan an event normally food is factored in, but if you could do an activity you can burn some calories. When I go out I also try to find restaurants with nice soup choices. You are vegetarian so I won't mention meats
I'd also suggest doing your research about what restaurants work better for you, that way when you all decide "where do we eat" you are not sitting there with NO idea and can speak up!
I also ask myself all the time is a good really worth eating when you factor in all the exercising you have to do to burn it off. LOL I love cookies with my coffee but when they are 100 calories each and it would take me 45 min to walk 3 of those babies off I rethink my choices!
Also when you go to your friend's house to eat could you pack some of your own food...some fruit, raw veges, etc. If you contribute to what's there you'll guarantee to have something for you.
Good luck!