How long should I wait?

So I did not try last month and no period yet like as of tomorrow I have a missed period my periods are always on the dot I was wondering how long I should wait to go to the doctor I feel like my thyroid is to blame I have had a hypoactive thyroid for about two years but was in remission a year ago just scares me because I have been ttc for two years next month just never feels like I will ever have my rainbow baby