This is my 3rd month using OPKs on my 2nd brand/type ... First two months I used first response but I always had a faint line.  So this month I choose to go with a pricier more recommended brand.  I've been using the clearblue advanced digital I'm going on day ten of high fertility according to the OPK did this happen to anyone else? Next month should I switch? Advice please 😕