First of all, I'm going to add to the comments about your feeling guilty about not being able to help your daughter. I teach Maths to an able class of 11-12 yr olds. Yesterday my 13 yr old daughter (who is recognised as being gifted) came home with a Maths homework I couldn't do! I just haven't covered the work she was doing (better add here that ICT, RE and English are my specialist subjects and what I teach most of!) I had to get her to ask a colleague. So no way can you beat yourself up for not understanding.

There are some great web sites out there; pm me if a list would help. But to me it sounds like your daughter's counsellor has it right - the teachers and you are spending more energy to get your daughter to do her work than she is. She needs to take responsibility for her work - but if she has ADD then that is really tough for her to do. Again, there are websites out there with suggestions.
Can you tie in homework to rewards? Could she have a "study buddy"? How about having a box full of the equipment she will need to do her homework so she can't use missing equipment as an excuse?

Take care, and don't beat yourself up!

Caroline