I would think if everything else has been ruled out it might be time to sleep train. We did it at 6 months and felt so bad doing it. It was easier and quicker than we thought it would be and all 3 of us are so much happier when we get sleep. Our doctor said that it would be harder on us than on the baby and he was right. Before we sleep trained we would be up 6 or 8 times a night and it was miserable. I hope something starts working for you guys!
Oh, hon, there's nothing wrong with him. He wants to nurse every time he wakes because that's what he does before he goes to sleep. Been there, done that, and it doesn't change unless you decide to change it (and sleep train). It's fine to NOT change it and just nurse him every 2-3 hours if that's what you want to do, but you can stop hunting for the magic no-cry fix for this because there isn't one.