IUD pregnant???

So I've had my copper IUD for over a year and I'm a little scared I could be pregnant. I had sex with my husband on August 13 and I have been spotting on and off, I'm tired and hungry all day. I've never spotted before so that's why this is weird to me... I started reading online a lot of stories about girls getting pregnant while on the IUD. It's too early to take a test and my period isn't for another week but I leave to Vegas the day of my period so I would like to know if I could be pregnant so I don't put the baby at risk by drinking... has anyone experienced this?? Help!