i didnt have many friends at that age either (also grew up poor and still am under poverty level now), also have a very small family. i relate! how is he in school? not being bullied or anything is he? you mentioned that you, yourself never really had friends either. perhaps teaching by example would benefit your son? are there school clubs he can join? if he is okay with you, his sister, and grandfather in respects to proper social skills and the like, i dont think you have much to worry about. also-some people are just natural loners. it doesnt certainly mean there is anything wrong.

id like to commend you because its sad that many parents would not reach out like you have for your sons well-being.

its important to be close to your children, of course, haha. but because he doesnt really have anyone else its important to not be overbearing as he could develop a total dependence on you.