BFP after BFN possible?

I’m a week late. Five days ago (2 days late for AF) I took a blue dye test that was negative? but when my fiancé pulled it from the trash a few hours later it showed positive with color. But still, possible evap line? I didn’t get hopeful.

Yesterday, I took a pink dye test and it was definitely a bfn.

Normal cycle is 26-30 days, like clockwork. I’m on day 36 — a week late! I am never this late. I’ve been exhausted for two weeks (I took a 4 hour nap yesterday and slept for 9 hours last night. Normally I only need 7 hours, total), had what I thought was cm, had extremely sore nipples, and have had an aching abdomen (not quite cramps, more like mini-aches). Today and late yesterday I had nausea and sour tummy.

I’m wondering: should I hold out hope for a BFP? Or is this just my body playing tricks? In other words: Has anyone experienced anything like this? And has anyone taken longer than day 35 to show a BFP?