My son is 3yrs & 4mos and is 100% potty trained but not poopie trained. He refuses to go poopie in the toilet. I can tell when he has to go #2 because of the way he acts but when I ask him, he tells me NO and when I try to take him to the toilet, it's a HUGE battle...And if he does go #2 in his underwear, he tells me he has to go AFTER he has gone. HELP!!!
This IS a huge battle, and you can't win it. I know it's frustrating when you know your child CAN do something, but WON'T -- but taking responsibility for his own bodily functions is an important learning and development step that only he can take. You can't force a child to eat, sleep, or poop -- right? He's giving you a strong signal to "back off" -- and if you think about it, you really have no other options.
But I'm here to tell you that, long term, the outcome will be BETTER if you let this happen at his own pace. It's not at all unusual for a boy of his age to resist pooping in the potty. And forcing a child to poop when he's not ready can result in serious constipation and other complications.
Here's what to do: Apologize for giving him a hard time. Tell him that when he's ready to poop in the potty, he will be ready. But tell him he MUST poop in a diaper or Pull Up, because it's too messy to poop in his undies. Allow him to keep a stack of Pull Ups, and let him pull one on when he's ready. But most importantly, try to release all the stress and pressure you've been feeling about it -- this isn't a battle you have to fight. He can certainly feel your stress and pressure, and it's not helping him get over this hurdle. It's also important for all the other caregivers in his life to be informed about your new style of handling potty training now, so he's getting a consistent message. Good luck!