Hello Shandi,
Welcome to NT. This is a wonderful group. You are not alone with your concerns over your son. We have all probably been there. Relax and look around and read some threads.

My kids are grown 24 and 21. I have had RSD for 9 years. My daughter expressed herself more than my son on how if affected her. CRPS is hard on us and we have to change the way we do things and not do some things at all. We have to ask ourself how much do we want to pay in pain for what we do? Somethings are worth the pain and some are not.
Your son is young and I know it bothers you more than him about what you have missed. As mothers we are born to nuture. When we feel that we haven't it's hard on us. You can still show your love in other ways. If he has a favorite show or video game watch it with him or play the game with him every now and then. Don't hover just let him know you are interested in what he is interested in. When school starts next year stay in touch with what is going on ask him how his day went. I know from experience with my son he may act like I'm bothering him but I asked anyways. My son is a quiet kid who likes cars. He liked to draw and I would always stop what I was doing and go over his drawing with him when he asked.
You may not be able to do field trips or volunteer in the classroom like you want but you can show you care in other ways.
It's OK to tell him on some days you will feel great and be able to do things and other days you won't feel good and it will be hard to get out of bed. But, that doesn't mean you don't love him any less. Give him a hug every now and then to afirm your love for him. Bake his favorite cookie if you feel up to it. Even if his favortie movie or show isn't yours take the time to sit in the room with him while he watches it.
RSD/CRPS changes enough in our lives don't allow it to change what you can control. Don't allow it to define who you are as a person. PM me if you want to talk.
Take care,
Sherrie