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.