BFN but still pregnant?

Bret

Anyone get BFNs on home tests but still miss a period and was pregnant? Thought I had implantation/ovulation January 1st. Should have started my period January 18th been spotting since the 17th. Day 43 on my cycle, pink when I wipe in the morning today was brown. Never enough for a tampon or liner. Help!?!?!?