How many calories would swimming burn?

Im a 13 year old girl who weighs 105 pounds. I am a competitive swimmer. I swim about 4-5 times a week. Well today before swimming i had about 1,500 calories. maybe a bit more. Then i got home after swimming and was STARVING!! I had two Buba burger cheeseburgers. Which was about 1,000 calories. at practice we had a REALLY hard set. we did a warmup, pre set, and hard stroke set then a hard free set. the practice was 2 hours. i was wondering is anyone had an estimate on how much i burned. Becaus i feel REALLY guilty for the cheeseburgers. i told my brother i was afriad of getting fat but he said i probably burned so much a swimming that i made room for the cheeseburgers? how much do you think i burned? my guess is 800-1000??? pls help. thanks