Disclaimer: I have no experience, just similar dreams..
I have read a lot on the subject though. One thing that is pretty constant, is the recommendation to live on the boat while you outfit for cruising. That is a pretty good litmus test. My wife and I would like to go cruising someday (5-10 yrs from now) , and we are going to do a very basic trial run by living aboard in our marina this summer for just a month. If we are still married..HA!, we will think about the whole summer next season, etx. The boat sounds fine to me (people have crossed oceans in boats much smaller, and if you are vigilant about watching the weather, np)... but it is all about what will work for you. Maybe 2 adults and a baby may find that too small, maybe not. The other biggie is experience. Sounds like you are a little short in that dept. Things on my agenda (besides a lot of miles under my keel) that I want to nail down before we leave: Learning a LOT about weather forecasting, engine maintenance and repair, getting my HAM license, getting some experience in snotty weather (not going to seek this out, but dont want the first time a squall comes up to end the cruise), etc. IMHO going cruising is not something to rush in to. If you are really committed, maybe living on the boat in sunny south florida for a year or two while you get ready would make sense. Let the kid's soft spot harden up a little and shove off when he/she will be able to have some memories of the trip
I hope you dont take this as a negative position. I wish you only the best, and as I said, I have no idea what I am talking about except for what I have read, but I do know that nothing can substitute for experience.
p.s. Here is a blog that really inspires me:
Dream Catcher - Welcome!
they are young and have been at if for a few years and are really living the dream.