Need help?!

I had sex Wednesday and woke up Thursday morning with heavy bleeding (keep in mind i am 20 years old and never had a period except when I was 15/16 had spotting for one day.) I'm going to endocrinologists and I made an appointment for my gyno which is on 10/21 but I am scared of what it can be. This morning  the bleeding went away so I had sex again and after sex the heavy bleeding came back. Is this my period for he first time or another disorder? I'm going to doctors and I will eventually find an answer, I hate waiting. Any feedback?!