Wow, I don't know what to feel. I have been so frustrated with my dd and she is only 3. Partly because she self initiated peeing in the potty before she was two. That totally through me off because I would have never expected it. But little sisters like to do what big sisters do. However, she also had pooping problems and problems with public restrooms. She would rather pee in the middle of the library than use the public restroom. Patience (and a pull up on longer outings) made that all bearable until recently. We had had like 6 weeks without any accidents poop or pee and she was regularly using public bathrooms to pee. And then all of a sudden we were having daily poops in pants. It was so specifically irritating because I "knew" she could do this. At first I though, hmm regression is normal and tried to ignore it. Then I moved onto being disappointed (not mean or punishing, just "gosh, I am disappointed that you pooped in your pants. . .). Then I even tried bribes (I usually don't bribe my kids).
Then, we had our well-child visit. I love our ped. but never ask parenting advise. So he asks about the potty training, etc. I mention that I am frustrated with pooping but am not real worried about it. He goes on to tell me his strategy, which I listen to patiently but decided that cleaning up the mess is easier than that agenda! Anyways, we go home, Kayla had an accident and it was her last. I don't know if it bothered her that I spoke to the dr. about it and that he talked to her about it (he was very nice) or what but I am very happy that we are accident free again.
One thing that I heard worked for kids who would request a diaper to poop was to give them the diaper but require that he/she sit on the potty in the diaper to do it. Something about helping them to learn to poop in that position -- also having a stool that their feet can reach so they can push into it with their legs. This worked for a friend of mine with her 4 year old. In our case, Kayla didn't want a diaper, would refuse it if we asked. So we weren't able to try this out.
Good luck!
Amy