IUD confusion

Leksi

I've had my IUD in since June 8th and just got it checked on the 12th, the Gyno informed me that everything was looking great and I'm free till 3 years later. My Boyfriend and I early the next morning were going at it and he cummed in me. He thinks we should be fine but I can't help but think we didn't wait long enough for the IUD to start working.