I just say "I"m an occupational therapist but I'm not working now". I sometimes say that I'm disabled but usually that's not my first choice if I can avoid it.

I have avoided reunions, college homecoming with a friend who really wants me to come, etc. because that question is so awkward, especially when combined with being 40 and never married, never in a serious relationship or even much of a relationship, no kids, etc. Where I went to college marriage is pretty much expected of everyone so it would stand out a lot if I weren't married and not using my master's degree which used to be my defense against not being married (I was too busy with education, adjusting to a new career, etc).