PLEASE HELP ME

So I'm 16, my period has never been regular but I started having sex over a month ago and I haven't got my period yet (even though I'm irregular I'm "9 days late"). My boobs don't feel different, I haven't been feeling sick or different, my appetite hasn't changed, just my mood sometimes (as usual) and we used a condom every time (last time was last Monday). Personally I'm not worried because of my period but what do you think? Should I be worried?