I’m vegetarian too (don’t listen to the fish oil thing, if you don’t eat fish like me!).
Anyway the thing that really helped me lose 70 pounds last year was switching what type of food I ate, not cutting down.
Whole grains are your friend. Anything made with white carbs - ditch it. Yes, this means white bread, pizza, potatoes, anything sugary (ANYTHING). You’d be surprised how much stuff has this nasty processed sugar in it. If it says corn syrup, especially high fructose corn syrup, don’t put that stuff in your mouth!
I recommend trying out the G.I. diet which basically focuses on whole grains and less processed food and is great for a vegetarian to follow. For a start, double up your vegetable portions and squeeze some of those carbs off the plate. Make sure you’re getting enough protein - it’s tough as a veggie. Try out bean dishes, tofu (it can taste nice, trust me), tempeh, soy products and eggs/milk in moderation. Omega-3 fortified eggs are especially good for us veggies. Also don’t forget to keep some healthy fats in there such as avocados (never more than 1/4 at a time), nuts and olive oil.
Spot reduction of fat is unfortunately a myth but you can work on the underlying muscles nonetheless. Core exercises such as yoga, Pilates or good ol’ crunches will help strengthen your abs. Bellydancing, burlesque, or the same core work will help around your hips. Arm exercises - use weights, there are some great workouts you can follow online with just a set of dumbbells at home, or you can join a gym and get into kettlebell and TRX workouts which I adore for their ability to make my arms look less like dough!
Cardiovascular exercise such as aerobics (legs bums and tums class!) or running is also great for helping raise your metabolic rate so you burn more calories, and just getting rid of fat all round. Look how thin marathon runners are 
Ultimately the best thing is to see a personal trainer or dietician and get some real analysis of what you currently eat and where you can make changes, but I do recommend the G.I. diet for learning a bit more about good and bad sources of carb, protein and fat. I lost about 30 pounds on it last year (the other 40 were on LighterLife a programme similar to Medifast, I recommend this if you want fast results but it is NOT a healthy and sustainable way to lose weight, it also tastes disgusting whereas good healthy low-GI food tastes amazing.)
