My Dad and brother were both "James" and absolutely LOATHED people who called them "Jim."

It's honestly really presumptuous.

I go by a self-chosen nickname -- Andi -- because I got so tired of people mispronouncing my given name of "Andrea" (I have one of the less-common pronunciations), so of course people misspell it as "Andy," even though my name is in my e-mail .sig line, it's the name I use on FB, etc.

The difference is that it's not a racial, sexual, or gender-based microaggression, and I *really* feel for the OP here.