See a doctor? Noooooooooo, as Blueiris says give it a few months with nothing and then start considering that. I once had 11 months with no period in my 30s, for no valid reason at all lol Periods can come late, early, not happen for a while or come closer together, the hormones involved only have to have subtle changes from - say anxiety - and before you know it everything goes a bit doolally.