Question about ovulation test

Hello all,

I have a quick question as I just had a baby last July (12 months ago) , and I am ready to start trying for baby #2. I do not get periods lol. It’s been like 20 months. I went to the Obgyn they said nothing was wrong, and I was even ovulating when they were doing their ultrasound. They just said I don’t have enough body fat basically and that if not having a period bothered me they would put me on birth control to start a period which I don’t want. I’m OK with no period as long as everything is OK. So I guess my question really is what are good brands of ovulation test, and after an ovulation test is positive what’s the “rule” for conceiving??