SUPER light period with Paraguard

Hello! I got my Paraguard in June 2015, and everything has been great. It's in place and life has been good. My boyfriend and I had continued using condoms because I was still nervous (silly I know) about going without. Earlier this month (2 weeks ago) we didn't use a condom, and now I'm supposed to be on my period and it's basically just spotting. I am typically VERY regular, and don't understand what this could mean. Any insight/advice??