The only way to really know if you have a psychological disorder is to have a mental health evaluation in person, however, based on the information that you shared in your question, I would say that you show traits versus a personality disorder. You are lacking some of the extreme behaviors that we tend to see in those diagnosed with Borderline Personality Disorder such as self-harm, suicidal attempts and impulsive acts.
Nonetheless, you are 28 years old without having had a serious intimate relationship and admit that your issues are getting in the way of you living a healthy productive life, which is enough reason to seek the help of a therapist. You must first learn to feel comfortable with yourself before you worry about what others think of you. A therapist can help you with these goals.
All the best,
Dr. Holly Counts