Need Help

Okay so my periods have been coming a little late every month for a few months now. It shows it should come on the 28th but I wasn’t expecting it until Jan 2 given what my periods were the last few months. I had sex on 19th, 29th, & 31st those times I could’ve gotten pregnant. I took a test yesterday and it showed negative. My question is could I still be pregnant from the sex I had on the 29th or 31st and it’s just not showing on tests yet or did I just miss a period this month?