Is the choice here to let the rest of the family go without you, or are you considering advocating for the other kids not to get to go during their childhood so that your kid can be the right age? While I think that under 2 isn't the age I'd pick for a once in a lifetime trip, I also wouldn't pick high school, and if you wait a few years, that's going to be the age of the other kids. It sounds like going right now is the right compromise for the age span as a whole. If you want your kid to have a trip they can remember, you can always go back in 4 or 5 years.
There are lots of things that an under 2 can't do at Disney, but there are also lots of things that they can do. Meeting the characters at character meals, playing on the playgrounds and splash pads, riding some of the simpler rides, seeing the shows, looking at the animals at Animal Kingdom and Animal Kingdom Lodge, and playing in the pool. It could be a fun trip.
I would also say that under 2 is a far better age than 3. Under 2 my kid was happy in the stroller watching the world go by, could nap on the go, and wouldn't have been upset by being too short for rides. At 3 none of those things were true. Plus once you're potty training or newly trained the lines are really problematic. Plus 3 year olds have to pay at Disney. So, if you're thinking of waiting a year or two, I would discourage it.