Bedwetting & Elimination Problems

Yup it's me again...
The enima only worked on dd for a week or so.
I probably should have given her more than one but the health risks scared me cause supposedly it's not the best thing to do.
Anyway is there another way to "clean her out"?

She's had enco and constipation ever since she started the potty training and she's now 7!
She seems to be cooperative at school but the second we get in the car when I pick her up she goes in her pants. So she does have some control of it to an extent. She survived all last year in Kindergarten too with no accidents.
I'm beginning to see that she's very "spirited" and "high needs" so certain ways to potty train her won't work, I have to be creative.
And I think this is why it's been so hard to get her cured from this because of how stubborn she is.

Her ped has been no help at all, and he won't give me authorization to go see a gastreotologist.
And the only way we can see one is with a ped's refferal.

So I guess I'm on my own with it. It's now time for plan B to rid of this once and for all.
Actually this would be more like plan S :P
So can I give her like Miralax without an enima?
She's been on Miralax about 2 months and it didn't seem to be doing anything so I stopped giving it to her. And we made frequent visits to the potty like instructed. What about Benefiber? I don't want to give her Miralax anymore, I want to give her something natural. So I need to find something that will "clean her out" Thanks!