Unprotected Sex after Mirena Removal

I had my IUD taken out on 23 Aug 2011 (two days ago) the doctor told me that I should start my cycle very soon but it could take a month or more for it to be out of my system and me be back to normal.
Last night my Fiance and I had unprotected sex, (one day after I had it removed) is there a possibility that I could get pregnant. We are not actively trying, but if it happens it happens thats the way we are looking at it.
I had the IUD removed due to some complications and I found out when I went in that it was stuck in my uterine wall. I do want children and I'm worried that it might affect my chances of ever having children.
Anything will help, I just wanna know what the chances are and if I should be worried about anything.