If you had sex 6 days ago and your expecting your period somewhere in the first week of September, you could very well be pregnant. The time line sounds like you may have been or just about to ovulate when you had unprotected sex. The white discharge is an indicator but not a for sure thing. I wouldn't freak just yet as it is to early to tell.
Many girls can tell something is different, they just feel weird like you said you feel. My daughter in law is "just" pregnant and she knew witin the first week, she felt strange as well.
You have a few more days until your period is expected, wait it out. If your period goes past the projected time, get a home pregnancy test and take it. There is a test out there called First Response, this test is so sensitive that it will tell you a few days before you even miss your period. I just hate to see you waste your money, but sometimes 20.00 is worth peace of mind, either way.