HI Mom,
I like the bouncing thing, sounds lilke it could work,
But your daughter is 2 now, have you tried the potty?
I would not gove miralax, try Aloe juice, prune juice, a sip of Coffee, Oatmeal, and fruits, ALL Are natural Laxatives,
however as you said the texture is fine, she is Just holding it in,
Sitting her on the potty, reading and helping her to relax,
can be helpful, PLUS its a great way to start her training
I have heard that when your child starts noticing and using her MUSCLES LOL its an indication she is ready to train,
Then when she goes, you can reward her, and make her feel sucessful, aswell as help her get comfortable with the idea of letting her poo out.
M