4 days late TTC

My partner and I have been trying to conceive for about 3 months now. AF is 4 days late, took a test yesterday and it was a BFN but there is no signs she's coming. We had sex last night and this never happens, but toward the end I had some discomfort and then after I was in some serious pain down stairs.. my friend who just had her baby said before she got her BFP she had some pain down there and the doctor told her it was due to everything changing, and not long after that it did go away. I've had really watery CM (I know that's not a good indicator), headaches, I feel bloated, little nausea here and there, and severe hot flashes guys, as well as constipation. I also stay tired all the time. It's just been a lot of different things for me this month that I've never experienced.. and the negative yesterday doesn't make me feel like this could be our month ):

Has anyone experienced this and got their BFP, I just want to kinda keep my hope alive.