Coming off of birth control pills can wreak havoc on your hormones. After your body having those pills helping with the level of hormones in your system, your body sort of goes into shock when the synthetic hormones are taken out of your system. It can take several months for your body to regulate it's own hormone production. Off levels of hormones can cause all kinds of symptoms...weight gain or loss, irregular or missed periods, fatigue, nausea..and many others. If you have taken 3 HPT's and all were negative I don't think you are pregnant.
I went off bcp's april 09 and my cycle was all kinds of wacky. Over the summer I went 64 days with no periods, I had light cramping, fatigue, sore boobs etc and thought for sure I was pregnant. AFter 11 neg HPT's, 2 neg urine tests at the doc and 1 neg blood test I eventually started. It wasn't until September that I started having my regular cycle back.
sorry i meant take a few months to regulate after coming off of bc
it is normal for a womans body to regulate after coming off of bc, i would give it until your next AF and if it doesn't show then i would speak to the doc about getting you on something that will help regulate your cycle