Wait wait, wait. You only get 3-4 hours of sleep PER NIGHT? My friend, it's no wonder you're struggling on every front. How do you expect to lose weight when you're in a chronically stressed state?
Get more sleep. You clearly have busy days so it might be tough, but there's no way you can get away with such little sleep. There's absolutely no alternative to a good night's rest, CONSISTENTLY, every night. If you can't cut back on study time, cut back on social time or whatever else you can sacrifice. Your body, mind and soul will thank you for it.