D.,
I'm a single Mom to a 2.5 year old little boy...and, I know how hard it is to find steady work and keep your child happy and healthy.
First, let me say this finding a school is rough. I have taken my son out of one because the program didn't suit his needs...so I get that. But, try not to make excuses for him, because it will start with that and move onto other things. Have you talked to the teachers at his school and found out what he's like at school? Maybe you can work with the teacher's at his school to help him learn to have more patience and deal with situations with more understanding of others. After all, as he gets older he's not going to be able to have his way all the time anyway. It won't fly in preschool and it will just get worse in Kindergarten and 1st grade and so on...
Changing schools gives him an out...he knows eventually you'll give and let him stay home with you.
With my son at first I felt enormous guilt for having him in daycare. That made my days with him stressful as I found myself making up for it, but being easy on tantrums and other things. But, this is the best I could do at the time. And, it was hindering my ability to really provide for him to the best of my ability. So, at the time he was 18 months, I found alternatives and my Mom retired and taught/cared for him at home. My family made sacrifices to help me and if you have that kind of support you should ask for the help. I know not everyone has that luxury...but, maybe you could find a different kind of school setting or home school.
Start working with him now on patience. Talk to him about his reactions to things. I wouldn't recommend discipline, because that will just confuse him and frustrate. There is still time to teach him about recognizing his emotions, identifying and dealing with them constructively. Try getting him some books that show various emotions, and help him look at them and see them. When you're watching TV (if you do) actively help him see what the characters are going through, and show him how they deal with that. I love shows like Franklin for that kind of stuff.
I also have been seeing a therapist to work on the issues of loss I feel over the relationship with my son's father...and our current state of no communication and anger with each other.
It's okay, I know how tough it is. It's really a process of doing it on your own. And, I commend you for doing what it takes to make your son's life happy and healthy. You are an amazing Mommy!!
I hope some of that helps...it's just hard to get all the stuff out that you want to in these posts.