OPK tests

Caitlynn • 29. Wife & Dog Mama. TTC baby #1 ❤️
Is there a certain brand you ladies recommend for OPKs? I've been using the ones from the dollar tree & I haven't seen any real results (Itll almost look positive, but then the next day negatives)
Its very possible I may not be ovulating at all (dr has unofficially diagnosed me with pcos) but I want to test for my ovulation anyway. 
Is there any types that yall would suggest that may not be as costly? I don't want to waste money if they're all going to be negative haha :)