I am dealing with the exact same thing. Not quite as long though... All I can say is, I am so sorry for you! I have a 4 year old who woke up one day and decided she was done pooping, and pretty much hasn't had a real bm in about 6 months. I've tried everything I can think of with no improvement at all. She's on Mirlax too. The Dr. told me it was just behavioral and that she would grow out of it. But I'm changing panties and clothes 3 or 5 times a day, she's in the bathroom every 20 min and still doesn't do anything. It's frustrating. If you hear anything that would help, please let me know.