My boyfriend and I had unprotected sex about 3 weeks while I was ovulating. Currently my period is 13 days late and my nipples are really sore, I get sick most mornings and sometimes puke, my discharge has totally been off, I have a constant headache, and soon after we had sex I had cramp like feelings in my lower left back and we googled it and it matched with implantation cramps. I also have been very moody. We took 1 pregnancy test a few days after my missed period and it came back negative. Once my period was a week late we took the other 2 and they also came back negative. Here in the future and upcoming days we plan on testing again. I've also never missed a period before and the latest it's ever been was like 3 days. What do you ladies think about this, pregnant or not ?

EDIT : i know the tests are negative but we took them really early on and if I am pregnant id only be 3 weeks. Isn't that still really early?