What is the best ovulation test to use?

My husband and I had two miscarriages, which was really hard on both of us. I have a total of 4 children and we are trying to have another one before it's too late for me to have another baby. My cycle was always every 28 days and than after the miscarriages my cycle is irregular periods, which is so discouraging and frustrating when I don't when I am ovulating. Please I need the help to figure out which test is good to use. Have a wonderful day