Poop is the hardest thing to train. My Pixie walks around in circles bf she poops so I usually just watch her and then quickly say do you have to go out?
I find if I take mine for a short walk after she eats she seems to do better. They are just little poops so try not to get stressed over it. she will do it in time.
If she hasn't pooped in a while try some canned pumpkin.