I would definitely go see your own doctor and have them do a blood test. Urine tests aren't as accurate as blood tests. Have you taken anymore home pregnancy tests?
FIRST OF ALL: Do you normally have very regular periods?? If yes, then I would have them do a blood test as well. You know all those stories about women who take home pregnancy tests, and even go to the doctor and their pregnancies don't show up with positive results. It's rare, but it has happened. So if your period still isn't showing up in the next week, see if you can get a blood test.
If no, some girls just have very irregular periods. They can go a couple months without a period. Good luck!