Late period.. should I be worried?

My last period was three days late but that was probably because I had sex for the first time in many months. After that period I only had sex one more time, the last day of my ovulation. Of course, I always use condoms cause I was still deciding which form of birth control I wanted to use. I don’t think it broke but right now I’m two days late. Some other possible factors could be that I just got home from my first semester of college and My diet has probably changed. Or Could it be the same reason as my last period? And How long should I wait before getting worried? I usually have a feeling before I get my period which is why I wasn’t so worried last time but I haven’t felt that yet this time