Opk problems

Corrina • have 4 kids with partnerthat passed away 7 yrs ago. me and my OH are TTC our first baby together

I have been using opks for about 7mths all was great always a faint line to start fertile week then positives on right day.

Last month all blank but body said I ovulated so did bbt

I'm in fertile week again usually they be see able lines by now and I have nothing at all.

Anyone any ideas? Do I not have LH at all now?