If I ever have to fill out an official form where there's a line (like this: _________________________) for me to write or type in my name, I always write my FullFirstName and LastName. It seems proper. It seems correct. When I applied for a job where I work now, FullFirstName was what I wrote in the box. They never asked if I had a nickname. They ordered my name placard and business cards with my FullFirstName, and my e-mail address alias also had FullFirstName.
So I became the type of person who goes by FullFirstName even though FullFirstName is kind of long with more than two syllables. It's begging to be shortened.
I'm not a stuffy FullFirstName kind of person! Really! When I introduce myself, I call myself Nickname. It's always easy to tell how a person met me. If you met me in person, you call me Nickname. If you met me through work or somewhere where I filled out a form (i.e., doctor's office), you call me FullFirstName.
However, there's a quirk. I despise the rhythm of my Nickname + LastName. Completely sucks. Independently each is fine but together it's a mess. It's short and awkward; it doesn't flow well because the last letter of the nickname and first letter of the last name shouldn't occur in that order. FullFirstName + LastName sounds much, much better. The longer version flows better; the syllables work well together.
So when I introduce myself, I call myself Nickname. And then people just sit there expectantly waiting for my last name, which I don't say. Not because I don't like it, but rather because it just doesn't work well with Nickname. Then they say THEIR last name, and I feel like I have to say my last name. But because there's that pause, I just say my last name. I let them put the two together and realize on their own that the name rhythm is just plain wrong. And then when I see Nickname + LastName in print (which doesn't happen that often because of my aforementioned hate of writing Nickname + LastName in print), I recoil. It even looks wrong on paper.
Alas, I'm cool with Nickname all by itself. When LastName is added, it looks wrong. It sounds wrong. It's just plan wrong.