WTH is going on

My periods are usually spot on, when I am calculated to get it, I get it. We stopped BC in March.
Had normal AF since then, until being 3 days late this month. Should have started early morning on the 9th and started late on the 11th after having sex. We also had sex the 27th (the last day I probably ovulated if not day after I probably stopped). We had sex on the 11th and hours later I spotted.
A normally period for me is light then heavier then light and lasts 4-5 days with normal to heavy clotting. This period was light thoughout and ended Sunday. On Tuesday (around when I'm supposed to ovulate supposedly) I started seeing very faint pink discharge and today it was more light brown more than pink.
Since the dates of those certain times we had sex, it makes it very hard to deternime if my headaches, light cramping, nausea, sore breasts, mood swings, fullness of abdomen and EXHAUSTION are symptoms or what.
I am a mother of a 4 yo but when I was pregnantwith her I had a VERY EASY pregnancy and labor. Never even had morning sickness with her and don't even remember missing my period.

Thank you for reading. PLEASE reply