late period 80 days

Hey yall i have been 80 days late on my period, and im not sure what the problem is? I had intercourse around mid july, but he had a condom and we are sure nothing happened, to be sure i tested first around mid august came out negative, still wasn’t getting my period and tested again around beginning of september, still negative. and then i took another one because i was still anxious about this late september still negative, so pregnancy is not one. I don’t know what else it could be, just started my first semester of college, not sure if stress is the reason but how do i even know if it’s stress i feel fine and have no symptoms of anything. I’ve been working out, walking, drinking plenty of water, sleeping fine(i get around 7-9 hrs daily.) so i’m concerned even more now and have no idea what’s wrong with me, havent gone to the doctor because i turned 18 earlier so haven’t had the time to like have a clinic or doctor or anything. Is there any place i can go for free that’ll help me maybe? any reason you may now for why this is happening? anything helps.