On pill, breasts sore, 3 neg preg tests, pregnant?

I am 22, I have been on the pill for 7 years, same partner my whole life, active sex life (2 or 3 times per week). Never had a problem. I started having breast tenderness aroung 10/29 and just thought it was related to my period since I expected it on the 7th or 8th of Nov. I got my period Nov 8th (previous one was 10/10) and it was moderate to heavy, like usual and it lasted until the 14th, which is normal for me (5 days or so). But, my breasts are still sore, almost more so now! And they seem bigger and firmer ( I am already a 34 DD!)It's almost been a month that they have hurt, and I don't know what to do! I took 2 first response HPTs (one 11/17 and one 11/19-morning) then I went to planned parenthood and had one done 11/19-evening and they were all negative. They told me that if I were pregnant based on when my symtoms started, that I definately should have a positive by now. I just need advice as to what could be wrong, and/or if you think I still could be prego or what? I'm worried because we are getting married Aug 9, 2008 (8.5 months away!) so this could be a real issue with the wedding date if I am! haha...

Thanks you for your help!
Krista