Do i have a mental illness?

ive spent the most of my life "alone" and by that i mean very introverted. i have brothers and sisters in which ive lived with and have had a number of friends. i feel alone because i never really had anyone i was comfortable talking to and expressing myself to. being the youngest in my family, most of my childhood was spent not being included with my older brothers and sisters. something fairly typical for the most part. the only person i spent alot of time with is my father, whom died when i was 13 years old, in my arms in fact. since then ive dealt with all of my feelings and thoughts myself and have been convinced that there was nothing really wrong with me. then i met my current girlfriend. shes the first person ive ever opened up to and likewise for her. she recently took a "break" with me and since this ive felt as thought ive lost everything ive ever wanted. i cant give her up and im constantly in contact with her. i feel so paranoid and have never realized how boring and empty my life was until she was in it. i feel like i might have a sort of trauma or illness from all of these events and was looking for some insight on what you think it might be. thankyou very much