Could I be pregnant or ovulation?

Quick question, how do I know if I’m pregnant before taking a test? also I just had sex like 5 or 6 days ago and it was unprotected like 3 times but I missed a day of birth control and yeah. I feel kinda weird and I’ve been having back aches, I feel really sore like my uterus, and what feels like cramps. but yesterday was my ovulation day so maybe it could just be that? Also I’ve been having heachaches and nausea 🥵. Could I be pregnant? If so like what are the chances?