Yeah.
If you are determined not to teach, don’t take out additional debt for a master’s degree.
I personally think it’s possible you may be able to teach but not at the high school level.
My husband (a college professor) was recently teaching a summer enrichment course to some middle school and high school students. He noted that there was a huge difference between the middle school and high school students. The high school students were intellectually capable of doing a lot more, but (and this is very important), it was much more important to get off on the right foot and impress them (which as you know is very unnatural for a self-effacing person). My husband, as a college professor, had never faced this problem–his college students come pre-impressed.
So, I suspect you might find middle school a better gig.
My dad (who has an MA in math and bailed out of K-12 math teaching years ago), says that 5th and 6th grade are the best grades to teach. They’re very responsible and capable, yet they’re still mostly respectful–they know they’re still kids, but they don’t require the sort of management that little kids do. My dad now teaches community college math with a lot of non-traditional students. I have to warn you, it is not a living! But it is a very enjoyable paying hobby for him, and he’s pushing 70, so at this point, he doesn’t need to do anything he doesn’t want to.
There’s also overseas English and adult education to think about.
So, I’m not saying to bail on your degree, but if you are 100% sure you’re not doing any kind of teaching, it probably would be a good idea. However, there are a number of different kinds of teaching.