Can stress delay or stop ovulation?

I have been monitoring my ovulation on and off for a while, I checked my ovulation back last April and was ovulating as it showed up on a test, after that I decided not to track my ovulation and leave trying to conceive for a while as I felt it was causing me stress. However I have been checking my ovulation this month and last and throughout my entire fertile window last month I didn't ovulate, which I thought was something to do with me doing the ovulation strips incorrectly. So this week I have checking every morning using clear blue ovulation tests and I am still not ovulating and I am on day 14 of my cycle, I have recently started an intense placement as I'm doing a degree and my work load has been horrendous which I'm juggling with being a mum to my 4 year old son. I have had sex every day during this fertile window so far regardless but I just wanted to know if there could be a reason im not ovulating or if anyone has conceived when ovulation strips haven't detected ovulation? I'm trying not to stress about it but we'd really like our son to have a little brother or sister and I can't help but think there's something wrong. We conceived my son within the first month of trying without any problems and I'm in my mid twenties so I should be fertile I think. Any advice or stories about undetected ovulation and pregnant would be greatly appreciated. Thanks in advance x