confused

Ok I need some advice because I'm really confused... So me and mybf have been having sex a lot lately for the past 3 weeks.. The past 2 weeks I had really sore breasts nausea fatigue constipation. So I took a test and it was negative, My period was supposed to come but it didn't. I was 5 days late until it finally came but it only lasted 2 days, I'm having back pain and headaches that never want to go away, I'm so picky on what I want to eat, and I've been very tired.. Could I be pregnant??