Hormonal imbalance? ??

Hello ladies, well I'm on cycle day 74 dpo 41. This has never happened to me before being this late for af. The most I've been late is 60 days. I called my Dr and scheduled a blood pregnancy test because I don't know what's going on with my body. Maybe it's a hormonal imbalance? My nipples have been sensitive for 2 weeks and it almost feel like a burning sensation, they don't hurt as much like before so that's a good thing. I've been testing since the beginning of this month and all the pregnancy test I've took are the same results negative. I don't know what to think because May, June and July I got my period and it seemed normal. August I didn't get my period and it looks like I won't be getting my period this month. Has anyone ever gotten a negative pregnancy test on a cheapie test from amazon and went in for a blood pregnancy test and came back positive? Thanks ladies and baby dust to you all.