Why am I not losing weight?

Lauren Asked: Why am I not losing weight?

Before Christmas I frequently eat popcorn, ice cream, etc. and had a pretty bad diet. I also rarely exercised as much as I should have.
Since Christmas I usually eat around 1200 – 1500 calories a day, of healthy foods, and do at least 1 – 2 hours of exercise every night.
I also drink a lot of water too.
In the last 32 days I have lost 2lbs and can't seem to lose weight in general.
Also, I'm 18 years old.
Why is this happening??
Advice and explanations are greatly appreciated! Thanks!