Homeschooling is a wonderful journey and you live in a area that has so many options. Where to start-we have homeschooled from the beginning and the more I look the more I find. Look up Washington Homeschool Organization (WHO). They have many resources listed as well as the homeshooling laws. There are several co-ops in the area, there is one on the plateau called Labyrinth which is all homeschoolers. There are many programs and classes offered to homeschoolers, we have been a part of Wilderness Awareness School for several years, the students gain a huge appreciation and understanding for the natural world.
You are doing your a children a huge favor by spending time with them and reading to them. It has been my experience that at this age they gain so much by their experiences in life they have a natural gift of learning (whether they are gifted or not) and want to know so much about our world. As you have found, everyone has a different style of learning and a different pace, the question is how do you want to facilitate that. When my kids were young we didn't do "book" school instead we did "hands on" we went to museums, on feild trips, read books, explored theater, went skiing, we had great learning opportunties without sitting in a classroom. And, the whole socialization issue is a myth. (at least in this area) My kids and their friends couldn't possibly be more social.
At any rate if he is truly unhappy and not thriving in his current situation I would lose no time in pulling him out. Anything you could do at home would be better than this unhappy situation. Best wishes, A.