PLEASE tell me this isn't implantation bleeding

Let me start by saying I don't have unprotected sex. I usually get my period on Fridays since I dropped the pill and it's usually pretty heavy and noticeable. I was pretty moody the days leading up to Friday, mostly just emotional, but that was it for pms. Yesterday I had sex and I thought I induced my period and I was happy as hell. The period was thin but the red color was right. After taking out a tampon and peeing this morning, there was nothing. I took two pregnancy tests Friday morning and Friday night and they were both negative, thankfully. Please tell me my cycle is just being weird because of stress! And going to a doctor right now is tricky, just saying...