Its amazing to see so many other moms with kids like mine!My son was 4 when he finally would go full time in the toilette! He would pee from age 2, not even wet the bed! He too has been a "Miralax" user and many other laxatives! What got him...went to grandmas for the week and Papa paid him a $1 bill for each time he went in toilette during the week, then on Sat went to the swap meet, and he bought like 5 or 6 different things with his money! Taking TV away helps too, he would want to watch his show, and hold it, having a DVR helps! (He's 8 now and a lot better) My daughter is 3 and to get her to go, I took her to Build-A-Bear when she would go all week, then we made a bear and got panties with Hello Kitty, to match her's, and each week if she went in the toilette she got to go back and get a thing for her bear. At Barton Creek mall, right across the way from Build-a-Bear, Pottery Barn Kids has a story time at like 9am on TUE, So we would make that our thing if she did her thing. It will be soon! Just love her!
I know you have so much to read...what about giving her a goal date, like Halloween, (maybe too early) Christmas, or Birthday, That you will have something extra special if you go in the toilette.