I Am 18 Years Old. I Am 5ft And 2in

I am 18 years old. I am 5ft and 2in and weigh 166 pounds. Just recently I had unprotected sex. I continued to take my birth control after words. Once I got to my off week, I didn't get my period right away. It came three days late. After getting my period, it started out light and then a small to medium sized, what I think is a blood clot came out. Then my period went to a medium flow with a sorta reddish brown color.