There is a word that many people, especially women have a trouble saying. That word is "no". Many people think that no is a dirty or bad word, and that they will be condemned and judged by others for using it. For those people I have several reframes of that word.
"That is not okay" is for the child who is making the wrong choice.
"I am not interested" is for the invitation to join an activity that you don't think will be a good use of your time.
"This is not for me/us" is for the request to volunteer that is not doable for you, or again is not a good use of your time.
I spent a good half of my life with the inability to say no to people for fear of what they would think of me. So many times I would say yes, when I did not want to and spent hours of my life completely miserable.
There is a problem with being the "yes" person, and that is you train people to use you as the easy way out of everything because they know you will do it. This goes for coworkers, friends, your church community, and even your family. In contrast, when you guard your time and you are honest with yourself and others about what you are capable of doing, you teach people to respect your time and talents. You will find yourself being asked for more appropriate requests. Your will stop getting manipulated into doing things that you do not want to do.
One of the blessings that comes with having a special needs child is that their needs become such a priority that it forces you to learn to prioritize and it necessitates that others respect your situation. When our oldest received his autism diagnosis and we entered into all the therapies and work with him to become more functional, I had to stop saying yes to everything. In fact, for a couple of years I did not take on any projects other than him and running our household.
About two years ago things have come around to the point that I can do some limited volunteer work, but it is on my terms. I give of my time and talents but I do so in a way that works and is not overwhelming or stressful. For instance, last year I helped a teacher one day a week with paperwork. I also co-chaired a committee at the school. Then I got pregnant with Mara. I am not doing volunteering in the classroom this year, and while I still do a significant amount of work for my committee, I resigned my chairmainship.
There is a time and season for everything. Right now my children are little and they take up the majority of my time. Having four children was absolutely the right choice for us and our family. We were spiritually called to do it and we wanted lots of children. This does mean what works for our larger family is often very different for smaller families. On top of that, living with special needs means that things that work for others would not be a successful situation for our oldest child. This means we just can't go to some events, and many parties are out. Instead of feeling bad about that, I choose to believe that there are other awesome things that we get to do.
Someday the children will be older and all be in school and things will change. Right now the PTO may be out for me, but I know there are lots of people who are glad they don't have to cut and count the soup labels with me.