Late period and 3 negative pregnancy tests

I came on here and was surprised to read that I'm not the only one having these symptoms. I went off the pill back in October and since then I have had regular periods. My cycle has been 31/32 days give or take a day or two. My last period was on 1/5/2007 so I'm 6 days late. I took a pregnancy test last Thursday and Friday and both came up negative. I took another one this morning and that came up negative too! My boyfriend and I are trying to get pregnant and I'm just confused because i've never been late before. I feel bloated in my lower abdomen and my nipples are very sensitive. I plan on calling my doctor tomorrow to do a blood test if I still don't get my period.