Coming off Birth control

Hi all ! I have been on depo since I was 18 (now 25) I got my last shot almost a year ago but I still haven’t got a period. Right Before that, I didn’t renew my shot for a few months because I wasn’t seeing anyone, I had on and off spotting for about 2 months and then got back on it bc I started dating again. Fast forward a year later I am not taking my bc because we would like to pregnant whenever my body says it’s possible after coming off depo. My question is how do I log this story in my calendar to get an accurate calculation of how my body works ? Keep in mind, I also didn’t have a period in those 7 years being on depo except maybe twice, the two times I decided to take a break from it and it took months for my period to return.