we were exaclty the same, and dd is 4! i bought him a big train set, put it at the top of the cupbard, where he could still see it, and siad he could have it when he started to do poos in the toilet. it sat ther for over 7 months, then about 3 weeks ago, something snapped and he's done every poo in in the toilet since. i think you ust have t wait until they're ready..