Confused on my body.

I am 27 yrs old. Have two kids. I am dating my high school crush. I'm on birth control pills. We started dating in October. I had a period 8 days long. 4 days later spotted for the afternoon. I did miss a few days here and there of my birth control. In November I had a 4 day period and 5 days later had a 3 day period. I missed a few days as well but not enough to mess up anything. My son is 13 months old. September my period was normal. Now it's December I spotted on the 7th for like an hour then yesterday the 10 when I pee, I see pink when I wipe. I took a test it said negitave. My hips hurt and lower back for about a week. My breast hurt. They are sore n heavy feeling. They have been really strong the last couple days. I'm tired all the time. Hungry all the time. What does all this mean. Please any advice would be great. Thanks.