OPK help while breastfeeding.

So I am using opks to get pregnant and still currently breastfeeding my first.

I usually get my period every 1.5-2 months (use to be monthly before I began breastfeeding)

Anyways do to how long my cycles have been I figured I would probably ovulate around cycle day 23-28. Well I took an ovulation test and it's very close to being positive at cycle day 11! (Not postive, but close)

Is that normal to ovulate early in your cycle I am guessing I will ovulate by CD 17... when I have cycles that last 36-50 days????