Could I be pregnant?

My bf and I always pay close attention to the app, we only have sex on days when I’m not ovulating and have a low chance of pregnancy. The last time we had sex was April 11 and I was scheduled to get my period the 18. We used a condom AND he pulled out. I’m generally pretty irregular- my average cycle length is 37 days but my last period was about 2 weeks late. There have been a few times where I have gone up to70 days without it. I have been running a lot this month to prepare for basic training so I just assumed it was late because of the excess exercise, or stress because of finals. I am really nervous because I am going to leave for the army in a month and I definitely can’t ship out if I’m pregnant. What do you guys think?