Two dives since open water. They were at Myrtle beach, on a wreck called the Henley...I think. Open ocean - small boat... 50 feet of water. It was fun, but tiring!
Galapagos?? Really????
First off, I applaud your enthusiasm, and the fact that you are looking forward to doing something like this with your son. Having said that ...
I only have my own experience as a reference. Going to Cozumel right after certifying, and going to 80' in clear, warm water, and doing a slow drift with the fishies, was about all the task loading and excitement I needed with my experience. I don't consider myself a wimp, weenie, or the anxious type, but it was enough of a challenge to make a memorable, exciting trip. Looking back, I would have thought of myself as being about 27 cents on the dollar if I had gone to the Galapagos after two dives.
Not saying you can't handle it, or that you'll meet with problems. But pardon me if I'm out of place, and not implying that I know it all ... I just think you're still in the "You don't know what you don't know" phase, and $h1t happens. As others have said, the Galapagos isn't (arent?) going anywhere. Get your gear (online is fine), get in some dives (like maybe 70-80 minimum in varied conditions) with it, and then go for the Galapagos.