People come in all shapes and sizes...emotionally as well; My experience has been that they shy away and let 'someone' else ask. Or they smack me on the arms and say, how the heck are ya?
Don't stop being yourself, I too am a private person; when how are you is a greeting and not a care/concern, I nod and say, Good day....if they say, hey, are you hurting real bad today....then I answer as I am feeling....
Losing those kinds of friends makes one think, where they really 'friends' in the first place....
It's hard either way, so I wish you the best. Hope venting here has help somewhat....