I can hear your frustration.
i was in the same postion as you till just recently. Im still B/fng DS who is 9 months old and i thought i may have been pg. But af hadnt returned as yet so i didnt have that to go off.
I had cramping, headaches, mood swings, ill feelings, sharp pains in ab, i even went off coffee for a short bit. BUT, it turns out after 3 weeks of this and 3 HPT (neg) that it was just my body telling me that af was returning. Ive only just got her back so now i can concentrate on what my cycles will be again. So far all seems normal but day 15 will be the teller as thats when i usually 'o'.

I wouldnt have taken that test you did as pos because most of them say DONT read it after 10 mins. And the fact that you did two others and they came back neg tells me you might just be coming down with something. In saying that though, every bodys body is different so if it puts your mind at rest to get a BT then go for it.

Good luck.