There is a difference between being labeled antisocial by others and having an antisocial personality disorder (ASD). Someone can be described as antisocial if they limit their interactions with people but it does not have the same meaning as antisocial personality disorder (ASD), as outlined in the Diagnostic and Statistical Manual (DSM) of mental health disorders. ASD is a chronic mental health condition that is characterized by not knowing right from wrong. Individuals with ASD also tend to get into trouble with the law, they can be violent, impulsive, and they generally express a blatant disregard for others. They also often have difficulty relating to others and their relationships can be dysfunctional. If you’d like to read more about ASD, please follow this link.
You may be not very social in the sense that you rarely spend time with others. You seem to avoid relationships. Some possible reasons for this may include fear. Perhaps you fear rejection or you have social anxiety. Social anxiety is characterized by an excessive and unreasonable fear of social situations. It can arise when an individual is worried that people may criticize or judge them. It is also a characteristic of schizotypal personality disorder.
Schizoid personality disorder is another disorder to explore. Hallmarks of this disorder are avoiding social activities where interaction with others may take place and not enjoying the companionship of others.
Another possibility may be that you lack the necessary social skills to be an effective communicator and this hampers your ability to relate to others. Additionally, you state that you’ve been a quiet person all of your life. Maybe you are used to being “the quiet one” and it is easier to remain in this familiar role. If you lived your life as an introvert, the thought of being more of an extrovert may be uncomfortable and frightening. It may also be that you’d rather be alone and do not prefer the company of others.
I am not sure if medication could help unless the reason you do not to interact with others is fear (i.e. social anxiety). Some individuals with social anxiety take antidepressants or anxiety medication and find them very helpful. On the other hand, if you do in fact have bipolar disorder (as diagnosed), you may find medication very beneficial. Perhaps the only way to know if medicine would help is to try it, under the supervision of a mental health professional.
I believe therapy could be very beneficial. If you are open to therapy, I would strongly recommend it. Here’s a website that may help you locate a therapist in your community.
Lastly, you also asked why your family is pressuring you to have relationships. I cannot know with certainty but I believe it may be because they are worried about you. Also, they probably do not want you to miss out on the many wonderful benefits that can accompany relationships. Therapy may be able to help you in this area and I hope you will consider it. Thanks for your question. I wish you well.