Frustrated

As some of you may know, we've been Home-schooling the kids since December. It's gone pretty well for the most part. We have more time to devote to the areas that each one needs extra help with. Mostly anyway. James has struggled with his reading since Kindergarten. It's gotten a LOT better, but in all reality he really reads at about a 3rd grade level. When he was in public school they had him held back (they say no learning disabilities), and if he were still in public, they would have him going into 4th grade this year instead of 6th like he should be going into. I'm looking for ideas to encourage him to want to read more.
Caitlin is about 2nd-3rd grade as well, she's had some issues as well with reading, but with her it seems to be more of the not wanting to sound it out in case she's wrong variety. I'd love to hear from any of you on ideas for motivating her to want to learn to read better as well.

My big problems right now are Caleb and Gabe. Caleb is currently doing 3rd grade work (as well as Caitlin), except in reading. In reading he's at about a late kinder level. He's learning, but very slowly. Math isn't a problem, he's great at it as long as it's not story problems lol. What I've been doing with them is if they need help reading something, as long as they're willing to try and read it and make the effort to sound it out etc, I will help them figure it out (book reading wise, for workbooks I read the directions and then help individually with issues as they arise).
Caleb doesn't seem to have any "drive" to want to learn things on his own, unless it's about snakes or scorpions. I've tried to make things about his preferred subjects, but there are only so many things that you can do.
Gabe is the hardest, and the reason that we break our school day into 30 minute (or less some days) increments. He HATES school of any kind with a passion. It gets better sometimes, but that's usually very very rare. He knows the alphabet, although he still reverses letters (usually p, q, r, m, w), can count to 10 with help most days (has even counted to 15 on occasion). But he has no excitement to learn, he doesn't want to be made to do things that seem to have no meaning for him.
He's working on pre-k to kinder level work, and has made alot (for him) of progress since December. But I'm really worried that maybe I can't do a good enough job with him. I worry that he'll never learn to read, never potty train all the way, never talk clearly enough. You name it I worry about it.
It's gotten to the point where I really wonder if it was so bad sending him to school everyday. The screaming and biting and tantrums and throwing things and all that. He got to the point for the longest time where we had to spell out the word school or he'd totally flip out and cry/scream/hit. He's getting to the point now where we can go past a school without him getting anxious, but it's taken since I pulled him in December. That's a LONG time to be worried. I don't want him to be like that again, but I also don't want to fail him as a parent or as a teacher. He's so hard to teach, and some days I wonder if I can reach him with as far away as he seems.
I guess I'm just looking for some reassurance that it does get easier, that he will learn.