The Potty Struggle

So the potty training has been a real struggle at our house. Our daughter, Sadie, is 6 years old, and we are still working, working, working, on getting this right. We have tried tons of different strategies. We bought a cute little potty chair. We got undies with cartoon characters on them. We tried the three day method. We tried taking her every 15 minutes, every 30 minutes, every hour. We tried no pants at all. We tried pull ups. None of it worked. None of it. She will go on the potty when you put her on, but in between times, she will never self initiate. She will never let us know if she needs to go unless she has to have a bowel movement. Unless I put her on the potty, she will wet her pants, panties, pull ups, through her pants, etc. and just sit in it and not care. At all. Anyone else struggling with this? Any tips or tricks you can share? How old were your DS kids when they finally got it? I'm so tired of buying and changing pull ups. HELP!