What’s going on

I’m so confused on what could be going on. My last period was September, I skipped the entire month of October. I rarely skip if EVER and if I do it starts the very beginning of the following month, I still have yet to start. I don’t think I could be pregnant because my husband just got back from Deployment on October 25th and that was my first time to have sex in over 8 months. I have a 10 month old, but even postpartum my periods have been regular. I just have no idea what could be causing it, I’ve never been this late.