The best thing to do if you can is go to planned parent hood and get a pregnany test, they can do it whenever, it cost but not too much at all. Call them and see how much first. You can also talk to people there about anything, they'll answer questions for you, just call.
Yes, planned parenthood can do a pregnancy test for you....but they can't do one today and it be accurate. You have to wait before a result will show up on any test. Planned parenthood uses the urine tests just like we can buy at wal-mart.
Rachel, if you had sex on the 19th and are due for your period on the 24th, I doubt you are pregnant. It's more likely if you had unprotected sex, however.
As the others say, wait it out and see if your period is late. Keep us updated.