R.R.
Dont feel bad I'm in the same boat! My son is 3 and a half and goes pee fine on the potty but still won't poop on the potty for us. My babysitter has better luck then we do, we are trying the reward method for every time he poops, bribes, and just sitting him down on the potty after supper every night and saying it's time to poop.
Good luck let me know what works for you!