Ovulation problems/tests

The first time I ever became pregnant the doctors measured me and gave me a date that I had conceived...this date was the a few days after my last period had started... few weeks went by and they measured me again and put it as a day my period started was the day I got pregnant. Well I ended up having a miscarriage at 10w5d. Every part of me feels it was because that tiny little egg had to survive a menstrual cycle and may have gotten damaged. My husband and I have been trying for 3 years. Ive always based my ovulation off what it says on here. I looked it up and discovered women can go through ovulation 6-14 days after her period starts. What is the best tests for me to discover when im ovulating? I feel like this whole time I may have just had a shorter cycle and had no idea.