Help!!! 16dpo

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Hey guys, so we have been TTC for a few months and we dtd on my ovulation day and before it which I track via temps and opk, I was due AF yesterday. My cycles are normally spot on 30 days like af appears during the night every single month and hasn’t the past 2 nights! I have cramps in my back and cramps in my legs / hips but no major period like cramps, I’ve had a sore throat and feeling quite nauseous the past week. I have had some brown spotting (like pin pricks) the past 3 days but nothing more than this. I had a bfn yesterday, just wondering if anyone has any advice? Thanks!