READ AND HELP PLEASE: Has this ever happened to anyone else?!

I'm about 2 months late on my period and I've taken 4 pregnancy tests and they show up negative, the most recent was 2 days ago and I did have sex a week after my period ended on May 17, I'm going to the doctor tomorrow but has any one been late after sex??? And if anyone has been pregnant what have been the symptoms, I've looked up a lot of stuff but I'd rather have other people symptoms.