Thank you for writing your query. I can understand your nature of keeping things to yourself and enjoying things alone. The reason for this can be your personality type, If you are an introvert who has always had few friends, then accept your personality type. You need the company of few close friends whom you can trust. It is not like introvert people are not accepted in the society. You just have to look for the people who share same interests as you. But later you mentioned, you were not like this in your childhood, there can be some issues in the past which we can discuss over chat.
Feel free to connect with me from the expert page.
Take care !!!