irregular periods Ttc

Hi. This is my first post and hoping some of u lovely ladies can give me some advice 😊it's our 3rd month of ttc. I'm usually really regular, 27-28 day cycles but last month for the first time ever my cycle was 38 days (we got married in this cycle so putting it down to stress & overindulging!) So struggling to calculate my ovulation date...Any one else had this problem?!