OP- I totally feel for you (and all the others on here who say they have similar issues). It is tough parenting this kind of child and nobody will get it unless they have one...I have one too. Mine is currently in the 9th grade and we are now at the point where we are letting him take ownership/responsibility and he is failing horribly. I know it must be done and quite frankly, I can't continue to 'hand-hold' anymore...I am too exhausted. It is plenty enough to manage my own self as well as all the other things we wives and mothers need to do...micro-managing another person on top of that is just so dreadfully hard.
In middle school, I was that mom who was always reminding him, organizing for him (made him a HW folder with a 'to do' pocket and a 'to turn in' pocket and I would put his completed work in the turn in pocket for him), finding out what his HW was (when teachers posted it on the HW website and if they didn't I would e-mail them) and telling him exactly what he needed to do (then it still didn't get turned in frequently and classwork didn't get turned in even more frequently). It was suggested to me by my inlaws, who are/were teachers, that I go to school with him and shadow him every day

. And my DS was medicated for ADHD all through middle school.
If I didn't do those things, he would have failed most of his classes (maybe all but PE and Art). The principal told me, when he was in 7th grade, to let him fail and I just couldn't do it. I now wish I had let him fail then, because high school grades are a bigger deal than middle school grades. I am now watching his college future fade away. But I think if he has to go to summer school or even re-do 9th grade, he will get why it's so important to do what he needs to do to pass.
We have found some other things that are helping us. We took him off of medication because he has trouble sleeping and every ADHD med we tried exaserbated it. He would hardly get any sleep at night and then go put his head on his desk at school and fight the entire day to stay awake (I had insomnia in HS and completely understand how horrible it is). He also has some caffeine in the morning...I hate that, but it's keeping him up and alert at school.
We found his currency...which has been very tough with him as nothing seemed to matter enough. One thing is that he does not want to stay in 9th grade next year while his friends all go on to 10th and another thing is that he REALLY wants to get a job as soon as he can...he wants to save money for a car (we told him that we would not allow him to work if his grades were bad because he should be spending that time to study and pull up grades).
He's also been going to therapy. And we've tweeked some other things as well. We've stopped being reactive...that's pretty important and very hard to do with a mouthy teenager.
Sorry you are going through this...it's stressful. Also, I am sorry that you are going to get flamed by some in this thread....that doesn't help anyone.