Late by 8 days ?!?

My period has been very consistent for the last couple years, I always start on the 10th every month , but last month I started on the 15th which was a little odd, well it is now the 23rd and my period is still not here! I had a light pinkish brown spotting around the 20th and have been spotting slightly since then but only enough to wear a panty liner. But it’s strange because I usually have a heavy flow that lasts up to 8 days, and even when my periods where normal I never would spot. Of course I googled my symptoms (10/10 wouldn’t recommend) side note: I am 20years old and am sexually active with my fiancé. Has anyone had this happen to them or have any ideas or suggestions of what may be going on?