Critique my workout please

[IlliniLou]

I weighed myself on Easter and weighed 305 lbs. Im 6ft tall with a large build. ya im fat, i know. Well since Easter i decided to do somethin. since then ive been on a exercise/diet regimen (its a start since i didnt exercise and ate whatever before this). I do have some muscle from doing power lifting for 4 years in high school but still its a lot of fat.
My diet has consisted of this since Easter:
i wake up and eat a power/protein bar, a piece of fruit, a multi-vitamin and 20oz of water
lunch- a homemade turkey sandwich or a 6 inch sub from Subway with healthy fixings and some baked lays potato chips and 40oz. of water
dinner- i'll have 40oz. of water with 2 lean cuisine meals or grilled chicken with mixed veggies

for snacks i'll have some grapes or somethin, and of course there are some meals that vary but i try to keep around the same calorie intake everyday. Im in college so if i go to the bars i just have a bacardi and diet coke.

For exercise i've been running 4 times a week for as long as i can run until i physically dont think i can anymore, then i'll walk back home. Lifting is about 3 times a week. i'll do bicep curls/tricep stuff/and benching 150 lbs as many times as i can (usually a set of 25 and then another set of 20)-also occasionally i'll go golfing and play basketball, this doesn't take place of me running or lifting though

Since Easter I've lost 15 lbs. Right now im just trying to lose fat. I think a big problem my whole life was that I had a very low metabolism.
So is there anything I can be doing that will help me? I'd be willing to take supplements to help lose fat but which ones actually work? Any workout suggestions? any diet suggestions? any input will be appreciated.