Am I pregnant??

Mariah
AF is due either March 25 or March 26. I took a HPT yesterday and it was a BFN. I am having a few pregnancy symptoms: nausea, sore breasts, frequent urination, fatigue, headaches. I took an ovulation test on March 11 and got a positive LH surge meaning omg I either ovulated on the 11th or 12th most likely. I had sex the 10th, twice on the 11th, and once on the 12th. Is there still a chance I can be pregnant even though I got a BFN? I am currently 11 dpo or 12 dpo. Has this happened to anyone else???