What could I be doing wrong??

I work out 5 nights a week for 1 1/2 - 2 hours...running, kickboxing, resistance machines, bike. I eat decent (varying between 1700 and 2100 calories and 25-30 grams of fiber per day), but I'm hungry ALOT and I've gained about 5 pounds since December. What am I doing wrong and how can I fix it??