AF late but still getting an BFN

Help! AF was due on the 10/2 (Monday) so I’m only 3 days late. Only symptoms I’ve noticed are sore breasts. I’ve taken the cheap pregnancy test that comes with the ovulation tests and it’s a BFN. I just wish I knew what was going on. Thinking about going to the store and getting a real test. Thoughts? (Been ttc since May, but stress at work has made my period very irregular. I’ve been doing acupuncture since late August to try and regulate it) what else, I have been drinking very little, trying to eat well and bought preseed but haven’t tried it yet.