Typically rent-to-own deals include rents ABOVE the market rate, with some non-refundable portion being applied to the down payment. This appearance of skin-in-the-game on the renter-buyer’s side is what might keep them in the deal 24 months from now. Giving them below market rent rate and essentially a free option to buy is a bit of a raw deal for you.
On the positive side, it sounds like you have it rented at a rate that about covers your monthly carrying costs. That’s not so bad.