8 days late...negative tests???

[wilcoxbl]

Hi there! I haven't been on the pill consistently since May of 2014. My period was regular in June, July, and August (each of them three days sooner than the previous cycle). My period in August lasted from the 19th through the 24th. My period in September should have arrived on the 16th. It is now the 24th and I still haven't received my period. I've had a queasy stomach and extremely sore breasts. I haven't had any pre menstrual spotting or period cramps like I usually get. I'm extremely tired and just feel "funny". I've taken, seriously, 8 pregnancy tests and all negative. My period is always consistent and have never been this late before. I called my doctor and she of course thinks I'm crazy and informed me it's extremely rare to receive a false negative. Any input? Has this happened to anyone? The unknown is absolutely killing me!