No I wouldn't say you picked a "wrong Ship" More laid would be a more appropriate way to put it.
My wife and I are 26 and 35 respectively. I wouldn't say we have enormous exposure but we have sailed on Carnival Legend and I can compare a little. And she, Regal Empress. (Now Defunct)
We've Sailed on the Golden in October for the Canada/New England run. And Eastern Carribean 8 day cruise in late May/ Early June. We've found the average age group to be late 30's to 70's. Carnival Legend had I'd say 20's through 70's. Very few kiddies on either cruise. School was in session and besides, we planned it to be that way.
We do not drink what-so-ever save for a nice glass of wine with our dinners. Two things we feel ruin our vacations are boozers and kiddies. Don't need any of that. Legend had a small group, I'd say mid 20's who were obviously drunk and did ruin a show for us. Without going into too much detail I did inform the cruise director and let's just say he took care of them real fast. But enough with that stuff. Our experience on Carnival Legend was magnificent to say the least.
Our experience on the Golden was just very relaxing, not as much activity, the most "happening" place as far as night life was the "Skywalkers Lounge" way up high at the back of the ship. You;ll get superb views from here. It is a Disco at night that closed at around 3 AM
But anyway, no you didn't pick the wrong ship. You'll have a wonderfull time. And remember, a cruise is what you make it.