How long does spotting on BC last?

I’ve been on BC since the end of October I started it when I started my period and there was spotting after it for a few days straight. I skipped my period in November with my BC and right after thanksgiving I started to experience spotting and it is now December and I have had spotting since the end I feel November. I’m wondering if this is normal for BC to have light spotting for a few weeks in a row