late period, pregnancy symptoms but BFN

Hi everyone! So I'm currently 4-5 days late on my period usually a 29-30 day cycle. Took a supermarket cheapie on Monday and a Clear Blue yesterday but both BFN (and then an evap lol) My predicted ovulation was Dec 22nd and we baby danced on the 24th (also on the 30th). This month I haven't used LH tests or measured my BBT so this ovulation is just going off the algorithm, so seeing as my period is late it might have been later Since early last week, I've been feeling like I could come on at any moment: cramps, back pain, generally being a hormonal mess and crying at EVERYTHING and having the usual food cravings for sweet snacks. But no AF has appeared. (TMI) I thought I had come on in my knickers on Sunday on a long walk in the woods but when I got home it turned out to have just been a lot of discharge, which is unusual for me to have THAT much, quite a lot came out in a few different instances over the course of the walk so I was convinced I was just bleeding. The last two nights I've also woken up with hot flushes in the night and had to go downstairs to cool off which is also unlike me. I'm going to hold off until the weekend before doing another test if I haven't come on already. But surely this late DPO I should be showing up if there was HCG in my system, no? Has anyone else experienced the same and still got their BFP? I should add, this is baby #2 and with #1, I had the darkest line 1 day before my period was due. Thanks in advance!