It's pretty uncommon for you to get a positive that soon before you miss your period. I got my positive a day after my period was due. Don't give up though.. wait a couple days and take another one, you still might get it. Besides, when you want a baby trying for a long time is so worth it!!!
Yes, I have tested before my period was due...got negatives and then one the day it was due or after got my positive. My son is now 2.