Is it normal for your period to be very late?

My periods are very regular and today I am 6 days late. I took 2 pregnancy tests. The first test I took was the second day i missed my period and the second test I took was yesterday (when I was 5 days late). I’m hoping the tests are accurate because they both came back negative. Assuming that they truly are negative, what could be the problem? I looked up some reasons for a late period other than pregnancy, and stress, PCOS, birth control, and menopause came up. Im 22 so i think thats a bit too early to go through menopause. Im not on birth control, I don’t have PCOS, and i wasn’t stressed until i didn’t get my period on day 2. So, can it be normal to just have a very late period or miss it altogether? I made an appointment with my OBGYN for next week because I’m super nervous and just want to know what the heck is going on. Hopefully Aunt Flo comes for a visit before my appointment. Otherwise I’ll be almost 2 weeks late. Anyone go through something similar and they weren’t pregnant? 😅😅

I guess it would help to say that I was supposed to get my period on 9/12. The first day of my last period was 8/14. My periods always last for 6 days and my cycle is 28-31 days.