Could I be pregnant? Still freaking out.

Hi i had sex july 13th. i had 1 heavy, 1 normal and 3 lighter periods since having sex. I have taken 5 pregnancy tests. First one was taken 3 weeks after sex and it was cvs brand and was negative. Then I took one 14 weeks after sex it was clearblue and it was negative. Than I took another one at 15 weeks after sex and it was clear blue and was negative. Than I took one 19 weeks after sex it was first response and it was negative. Then i took the most recent one yesterday almost 20 weeks after sex. Could I be pregnant? I have been working out alot lately. Atleast 10 hours a week weight lifting, running, and doing core. I also have not been sleeping peacefully at night and have also been eating alot less.