Possible cryptic pregnancy? Paranoid and freaked out

So I had a pregnancy scare that I thought had ended awhile back. Here are the facts.

I had withdrawal sex in April while on the combo pill. Weird period in May. Went to doctors 5-6 weeks after sex and had a transvaginal ultrasound and pee test. Negative. Over the next three months I had more pee tests and a blood test that counted my HCG, which was less than 1. I then had ANOTHER transvaginal ultrasound in August which, again, showed nothing.

But my symptoms have been

•increased amount of discharge (this also started after getting implant in)

•some back pains

•kick-like sensations/spasms in the abdomen (ranging from under my rib cage to right above my pubic bone)

Is it possible to have 12 tests and a blood test all false negative over a course of a couple of months? On top of 2 transvaginal ultrasounds?