Late period, scared I'm pregnant

Hi guys so I missed a few of my pills just after my period, about 3 of them and when it came around to my period it was 2-3 days late and much lighter than usual and darkish red/brown at the beginning, I usually get that at the end. I thought I might of been pregnant and was constantly having panic attacks because I had unprotected sex around the time that I missed my pills, so a few days ago I took two pregnancy tests and they both said negative. could I have tested too early? or could my period have been a little off this month because I missed quite a few of my pills. 😊