Not ttc but trying to learn my body

I am 27yrs old with a 1yr old n on mirena. I never learned how long my cycles are n wen I ovulate bc it was always irregular my whole life until 2periods ago. Last week my sex drive was higher than normal for a couple of days n this week I have been cramping n having mood swings so I thought maybe bc my period is finally regular I am having symptoms from ovulation n I was right. I am not ttc but trying to learn my body finally and hopefully use this info one day when my husband n I plan on making baby #2. If anyone has any suggestions on when to test; like morning/night or what cd is a good day to start testing, where to purchase test strips for a good price, what brand is best, or anything at all would be greatly appreciated TIA