My missing period story. Help

Last 3 cycles Sep. 10th Oct.13th and Nov.8th. Glow said Dec. 12th was my cycle day this month but its a no show. I had sex only on Nov.25 unprotected Nov.29th(pullout) Nov.30th unprotected Dec.5,6,&7th unprotected. I took a test last night and it was negative. I have some on and off cramping for about a week but no other signs of it coming or no signs of pregnancy. I've never been this late before and I'm not under stress. So I'm wondering if I could have gotten pregnant in the beginning of dec and its to early to detect or maybe I'm just skipping a period or running a little late. Thoughts?