Losing virginity and being late. Me.

Hello. I'm almost 19 years old and a month ago I had with my boyfriend sex for the first time. (it was the first ime for both of us). My period was never late but it's 4 days late and I'm worried.. I took the pregnancy test it showed negative obviously cos my boyfriend never finished inside of me and also we used condom every time. Also, we had sex a lot of times almost 6 times in a small amount of days, in a week probably 3 times. I don't know what to do, I'm really worried cos I know he didn't finish inside of me , but I did swallow his sperm 2 times but I doubt that this is a way of staying pregnant. I don't have morning sickness or any other pregnancy symptoms. I have thyroid desease and Polycystic Ovary Syndrome which caused problems in my period before but it was treated with medication I took. Is it normal to be late after losing your virginity and having sex several times..? Please help me..