We are too similar! I often have wondered the same thing about my DS. He is "normal" to me and he doesn't seem so different. I get reminded once in a while that he is an outlier. I occasionally even wonder if maybe the test results were wrong. It's totally ridiculous! He has proven several times over that I shouldn't question it.
I also have a younger daughter and have a hard time not comparing them. I was concerned too about her not hitting the same milestones as quickly. (She has her own things she excels at, but normal with letters/reading.)
I changed schools this year and have had to answer that dreaded "why" question a few dozen times. If I said anything about giftedness, it was not well received. I think the term "gifted" is tainted. What I found that worked as a better, more accepted approach to that question was to say that "he is working beyond his grade level and his former school could not support him". It says everything it needs to say. His new school isn't a school for gifted kids, but they are doing an awesome job so far and he loves it. Good luck!
