How long would it take me to lose 15 pounds?

Hi I'm 18 and 200, and I'm attending Massachusetts maritime academy in august the 20th. I would hope to b around 185 before then but I need help. I have been running for about a week and a half now with no results at all. This is my usual workout everyday: I run around my schools track for a mile. After I finish one lap, I do 20 pushups. I repeat this until I run a total of 1 mile no rest. I am working with my father also roofing. And by the end of the day I am exhausted and sweating all day. Yet I have not lost any weight whatsoever. Please help