I discovered this when I went to college and was very surprised to find that I (I'm half-Asian, half-white) was also included in this category. Until then, I had only heard "person of color" to refer to African-American or black people, so that was an education for me. Not to mention, I'd been trying my hardest to ignore my Asian heritage, but I won't get into that here. So it was jarring for me to be referred to as such, but I've gotten used to it.
My college had several groups, the Black Student Association, a group for southern-Asian, Mexican, Latin-American students etc. I didn't fit in to any of those categories so I was extremely happy when I discovered a student group for those of mixed-race, although there were very few of us. It was gratifying to have people to talk to about things.
Combinations are nice. It's cool you found a group of people to hang with. I gave up ever having that long ago. I never fit in anywhere. A perpetual outcast. Must be nice to fit in somewhere