I have yet another possible reason for these social difficulties one tends to experience: If you are smart, you have to hide it. It sounds plain, but you may be able to remember someone making fun of you in your childhood for using "fancy words", excelling at math or literature or something like that. I am not sure if I can fully identify the cause of this behaviour on others (maybe a defense mechanism) but I find it to be empirically true. Personally, I went most of my very early life complying with the constant need of feigning modesty, which made me reluctant to participate in quite a lot of conversations, and I thus believe it to have been an obstacle for my social interactions.

I notice that you often wrote "intelectually gifted", but never "intelligent" nor "smart". Is it just eloquence, or might that be a way of modesty that -such as myself- you have got used to?