Confused

I am currently two months TTC after only having one shot in July 2017, I had a light period in November and 2 days late for my December period. I've spotted off and on all of December (pink, brown, and red), I've gained apx. 8-10lbs, my nipples have gotten bigger and darker, certain smells make me nauseous, and I can't get through the day without a nap or two. My cervix is high, soft, and closed, and I have gotten two negatives this month. Has this happened to anyone and they were pregnant or did you get AF?