period is a week late???

so I have an IUD, and i got my period a little late last month, but its never been a week late. i may have had some spotting ealier this month but im not exactly sure. i did have sex in between periods, but he never came in me and nor did he put it back in after coming, so the precum probably didnt have active semen. im wondering if i should take a pregnacy test or just wait? I dont really want kids right now, and usually I'd use a condom but it was a spur of the moment thing, it happens to the best of us, right? can someone please help me?