Spotting with Copper IUD

I had my Copper IUD inserted on February and so far I've had 2 normal periods more cramping but it was fine... this month i was supposed to start my period on the 18th according to Glow but ive not had any symptoms that it's coming. The thing is that I've had some sticky brown discharge (sorry if TMI) that i thought it was old blood and I've also been spotting but it's always brown not red... so i was wondering if this could be caused by the IUD, if im skipping a period or other. ive also been sexuality active with the pull out method

Thoughts?