TTC baby number 4!!!

Hi my is Kristin, Im a sahm of 3 kids, we've been trying for a 4th baby for over a year, I had a miscarriage at 7 weeks in April of last year, then a chemical pregnancy in July, I've never had problems trying to conceive and all my other pregnancies were perfect, Ive been tracking my cycles and just started using opk's but Im really confused because there all over the place, can anyone help me with this? I dont get it 😔