How much and what should I be eating a day with this schedule?

So here's the deal..im a 16 year old girl and im going to be a senior. Every day I wake up and I run about 5 miles. Then in the middle of the day I will bike to my college class and home which is about 15 miles round trip. I am also a state level swimmer and have a 2 hour swim practice at night about 3 nights a week..this practice I also bike to which can be 2-10 miles roundtrip depending on the night. I honestly still feel chubby despite the fact I usually do all of this and eat about 1200-1400 calories a day. Its very frustrating. What am I doing wrong? by the way...I don't eat junk ever...I make myself egg whites, fruit, turkey sandwiches, oatmeal..and I do a 30 minute ab-workout after running each morning. Why do I still have a small stomach and why do i still feel so uncomfortable? please help me..what am i doing wrong?