Almost the exact same thing happened to me, mine was red/green. Job prospects were poor at the time, early 1983 so the Army offered me a bigger bonus for infantry school at Ft.Benning Ga. I took it and little did I know what I was getting into........ :shakeheadI didn't find out I was colorblind until I took the service entry exam at 21 years old and then found out I was color blind in the brown/red domain. I had an associates degree in electronics and stood to get a bonus for joining but because of that was denied a job in my field so hence took a job in the private sector.
I can't tell the difference between some browns and greens. I went to University whose colours were purple and white but I initially thought my school jacket was dark blue and white.
I cope by asking people around me or if I have to describe something or somebody I use other characteristics like shape or size. It gets really frustrating with clothing so my wife picks out what colours I wear.
P.s. I'm Canadian so don't mind the "u" in colour