What you’re describing doesn’t sound like a personality disorder.
It’s important to know that we as people change over time. Just because we were one thing or acted a certain way before doesn’t mean that it’s bad if we change in the future. Sometimes our priorities change, our interest waivers, or certain things just aren’t as emotionally rewarding. It could simply be that you’ve grown, and you’ve started to figure out what matters more to you. That will likely change again in the future.
It could be too that you’re dealing with some comorbid depression. The isolation, loss of interest, lack of sex drive, difficulties with concentration, and other things would seem to indicate at least the possibility.
Personality disorders have to do with interpersonal relationship problems or problems with regulating your own emotions. You didn’t indicate a lot of those issues, so I personally wouldn’t worry too much about that.
Are you getting treatment? Do you see a therapist? If not, this would be a great opportunity to work with one and explore these ongoing issues.