According to Dr. Miriam Adahan an introvert is not necessarily someone who prefers to be alone although he can be alone without feeling lonely. Rather, an introvert cannot stand large groups but prefers small groups of long-time acquaintances. I myself am in this category.
Of course, there are degrees of introversion as with anything else. From your question, it seems to me that you are not extremely introverted (otherwise you would not be asking it). IMHO, you should seek a small, accepting group/shul.