IUD and Possible Pregnancy

So I got my IUD on July 9th and my boyfriend came home from the Marines on the 19th. My last period ended on the 7th, but I am like 4 or 5 days late. He finished inside of me almost every time. I have never been able to feel my strings so I can’t check them. Ive had some discharge and cramping but no bleeding. I don’t know what’s going on. Should I be worried or am I just paranoid cause I’ve never had an IUD before?!