late period

so on eve it says i’m 7 days late and then on the flow app it says that i am 14 days late. i took a test sunday and it was negative and then i took one again today and it was negative. i did take a plan b in my last cycle so i’m not sure if that’s the reason as to why my period is so late. what do i need to do? do i just need to wait on my period and not stress or what?

i did have a very stressful two weeks so that could also be a factor.