Welcome!
That doesn't sound like hothousing to me. Remember, that some kids wouldn't pick those things up even if their parents hothoused them so your son is obviously (to me) a very bright boy. I'd get him tested if the money is available. There is a lady in NH named Sandra-Leigh Sprecker Marlow who does gifted testing. Have you talked to your local school district yet?
How did you teach him to read? I ask because my DD4 is reading but it is very hard for me to assess what level she is reading at because she doesn't like reading aloud or to me or being asked about. She shocks me with the words she can read and when she is willing her fluency. I'd actually like to help her develop better fluency since I think she would like that, but am not sure how best to work with her and was wondering how you taught him (I have no probem with someone intentionally teaching their child to read if the child enjoys it so don't worry I will think you are hothousing. I am not so touchy about that issue as some people are).
Good luck.
