You're really not supposed to check them a few hours later; a home pregnancy test is meant to be read only in the first ten minutes or so. I'd take another test, an early-results kind, and follow the instructions exactly, including the part about not reading it later. If you want to be sure, get a few of the Dollar Store tests (because they are cheap) and take one every few days. If you have access to a doctor who will do a blood test, it is definitely faster and more accurate, but also more expensive. Also, some docs won't do a blood test and will just run you through a urine test that isn't any more accurate than the sensitive home tests are.
You might very well be pregnant. I think those home pregnancy tests are most accurate 5 days after your missed period so you may want to wait until the 7th and take it again. If you can take the blood test though, that is more accurate. Good Luck.