Added: after thinking and remembering the process for my grandaughter, I need to change her time line. Around 2, her mom took her to the bathroom with her. She practiced sitting on the little potty. She was probably around 2 1/2 when they bought the Elmo potty.
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I suggest you treat sitting on and using the potty as no big deal. When you bribe her, she gets something extra. It's to her advantage to not sit on the potty because she gets something when you bribe her. And she'a in control.
Eating and pooping are the only things she has control over. At 2, she is trying to find ways to affect her world. Perhaps by ignoring potty issues and encouraging her to make other choices would help. Let her choose between 2 outfits. Have her choose the book for bedtime stories. Give her more power in other parts of her life. And never insist that she has to sit on the potty. Continue to encourage her to use the potty. When she won't sit on it, walk away with no further comment.
Don't immediately change her diapers. Let her be uncomfortable in them. When she asks to be changed, be too busy to do it now or just not do it.
One of my granddaughter's didn't want to sit on the big potty or her little one. Her parents took her to Target to choose another potty. She chose an Elmo potty that had a back and could be "flushed" by pushing a handle to make a flushing sound. Most of the time, she would use it for urine. If she didn't want to use it, no big deal. They took her to the bathroom at irregular intervals asking her to sit for a few minutes. They also put her in training panties. To be wet was uncomfortable. She wore pull ups when they left the house.
She was around 2. In a few weeks, she was willing to sit long enough for success. She turned 3 in August and i realized she had been using both the big potty and her own potty on her own, without reminders for 3 or so months.