Has anyone had mulitple BFN's and were still pregnant

Cassi • Single Momma of Four Graci 5-7-15 Graeson 9-7-16 Gabriel 8-6-19 and Baby G due 6-25-22! Angel Momma.
I was wondering does it take longer for some women to test positive than other cuz ive had multiple BFN from dollar store tests and i M now 4 days late for AF im loosing hope here!!!