This is just a simple question but it's driving me nuts! We've decided on the name for our baby boy- Finn. It goes well with our Irish last name (O'Meera), and we both love it. So the dilemma is, if we intend to mostly call our boy Finn, then should we just name him Finn and get it over with? I like the sound of the longer and more formal Finnegan, but my husband disagrees. Middle name will be one syllable (a family name). Any thoughts?
I have a similar situation in my own family. With one of my children, we decided we wanted to name him X, but there was a longer version of the name---let's call it XZ---and we felt like maybe it would be better to use it as the Official Name. After much discussion, we decided we preferred the name X, so we named him X.
BUT! I'm sure there are lots of people who go with XZ and later are very glad they did: for flexibility, for formality, for nickname potential---lots of reasons. As a counter-example, with one name we were considering, we liked X but not XZ, so we decided not to use the name at all. A difference: in that case, X is widely considered to be the nickname for XZ; in the case of our son, XZ is only sometimes (narrowly, as it were) assumed to be the nickname for X, and is also a stand-alone name. And to me, Finn seems more a case of narrowly than of widely: some names are really JUST nicknames and some are shorter versions that are nevertheless full names, and Finn is a shorter version that is nevertheless a full name.
I think in your case, I would ask you which you PREFER: do you prefer Finn, or do you prefer Finnegan? Both are stand-alone names, and I think you're safe choosing the one you PREFER. Either way, I don't think later you'll think you've made a mistake.