Help, I believe I am pregnant

I had unprotected sex feb 28th through march 4th. My period was due that weekend and it never came until the 6th and was light and only lasted 2 days and I have heavy long periods especially when I miss a pill. Very odd as in I skipped my pill a couple times that month, but now 14 days later I started spotting pinkish brownish sticky discharge, it was pink then later changed to brown and shows only when I wipe, and now 3 days later It barely shows, noted since I started back on the pill after last cycle I have not missed a pill so it was weird I was even spotting, I am getting angry easily, sad/depressed over nothing and I'm exhausted more than usual, I also have light annoying cramping and fullness feeling in my abdomen? Sometimes it's worse on the left than right, but also it changes from right to left. I am dizzy a lot and I am getting hot flashes. My boobs don't hurt and I can't tell if I'm bloating, but I am peeing a lot more than usual. Also took a first response test that 14th day and it slowly turned negative. Help please