Only you truly know your limits. Don't get stressed by someone elses idea of what you should be doing.
Before we could afford for me to stay home with the boys people at work were always trying to get me involved with something that would use up a lot of my free time. I consistently told them that any free time I had was for family time since I worked and DH worked and the kids had to be in day care all day Monday - Friday. I refused to be bullied into it.
After I stayed home with the kids and they got bigger, I had more free time and did a lot of volunteering while they were in school.
And I have helped make pillowcases and quilts for good causes. But I chose when and how.
I have learned the hard way not to write a check. Did that a few years ago to help hurricane victims. It was a one time donation - DH gives regularly through his paycheck. Because I wrote a check they had our personal information and sent us a monthly bill disguised as a request for money. Now I either give cash or money orders. Lesson learned.