Mommas that have gotten pregnant while breastfeeding...

If I'm still breastfeeding my 17 month old, and I've had 5 post partum periods.... This month was my first month using opks and I got a positive.. Would you think I can conceive? Also, does him breastfeeding effect my chances of getting pregnant anymore or no since I'm getting periods and ovulating. And lastly, would breastfeeding effect an opk and give you a positive for any reason?