PLEASE HELP!!!!

My period is always pretty much religiously a full week. 6-7 days is the usual. Maybe 5 if im lucky but never less. I’m on the pill. Although I have missed probably 5 within the past two months. We had sex the last time either the beginning of the month which would’ve been my fertile window or the next week after, I’m not sure which week it was or what day. I got my period last month and I was supposed to start Wednesday/Thursday/Friday (normal starting days for me) and I had what I thought was gonna be my period Friday. It wasn’t normal though. And it stopped. I havent had it since. I have had some brownish discharge though(not much at all, light brown). I have the urge to pee more, headaches (common for me though), my hips were KILLING me Saturday and Sunday and my back has been hurting. What is going on? Please help

Just figured out if I did conceive it would’ve been Jan. 9th. This day is two days after my fertile window ended. Should I test? What’s going on please help