TTC while breastfeeding

Any other mama's TTC while still breastfeeding? We have been trying for 4 months now. Before we wasn't actively trying but we wasn't preventing. My son is 2 and nursing with no end in sight. I know breastfeeding can prevent ovulation in the beginning months but can it still effect my fertility now? He nurses A LOT! like every 2 hours and through the night. I get positive ovulation tests but can't seem to get pregnant. I never took birth control either. Can I have a positive ovulation test and not actually ovulate?