Could I be pregnant?

I have been doing opks and temping for about a year. 3 months TTC. Was only able to have sex twice and only the day before ovulation. Took a pregnancy test 10 dpo and two 12 dpo. I am now three days late for my period, 15 dpo. I "feel" pregnant. I am nauseous almost all morning, feel bloated, headaches, hot flashes AND chills (random times), lower back pain, and I committed last night (tmi sorry). All test have come BFN, but with all these symptoms and no AF, could I be pregnant?