AF arrives exactly 28 days each month..

As the title says, my period ALWAYS comes every 28 days. I've only recently started chatting temps etc. My question is, this month I ovulated on cd18, and today is cd29, and still no period. Glow has pushed my period back to come on what will be cd30. Surely once before (out of all the periods I've ever had) I must have ovulated on cd18 or later, and my period still came on cd28? Is this a good sign? I did preg test on 9dpo, and bfn 😭 thanks to those that will respond 😀