There are lots of theories about personality etc. You probably will find most of what you are looking for within abnormal psychology / counseling.

You might find it interesting to read about the history of psychiatry. There are a lot of weighty tomes, I'm afraid... You might find that early psychiatrists like Freud and Jung are interesting. Psychiatry started out more as you say but it is largely about prescribing drugs these days. Clinical psychology can vary a bit... You might not like cognitive behaviour therapy / behaviour therapy... Finding it too... Soulless... Or... Something...

There are a number of interesting people... Kohut. Klein. Winnicott... You might like psychodynamic / analytic theory.

With respect to a future career there are a lot of people wanting to do this kind of thing... But someone has got to do it. And everything is competitive these days. So...