I went to school with a guy whose legal name was Danny. Not sure if he ran into the same problems you did later in life.
My name's short, one syllable, and doesn't lend itself to any abbreviations or modifications. I've wished I had a name that DID have a 'full' version and shorter version; I'm a bit tickled by the practice of being called by your full first name initially, and then once some level of friendship is reached, being called by a shorter name. It's very much like languages that have formal/informal pronouns, like "tu" vs "usted" in spanish. A friend spent the year between high school and college in Germany, and a woman there she'd become friends with invited her to use the less-formal terms (I don't know or remember the German forms). She said something like "sure, great" in return, and another friend kicked her under the table and whispered "This is kind of a big deal". Later that night, the woman offered a toast to their "newfound familiarity" (I guess it sounds better in German :-) )