I was kind of like you describe for many years. Except I was not disturbed by it the way you are. I was only disturbed by the fact I wasn't disturbed by it. I had fallen terribly in love and that in itself left me confused for years. It never felt like a depresison, but it was debilitating for sure.
I only got out of it when I got actually depressed when my emotional self felt the reality my intellectual self was alway aware of, but tried to rationalize away to protect my emotional self. (hope that makes some sense)

I have no answers. Sometimes it feels like it is just silly chemicals deciding how we feel.
But I have changed, in some way. I used to despise people or strangers. That was one reason to avoid as many people as possible. Or maybe it was just anxienty I had, even though I don't see myself as an anxious person.

Right now, I wish I was 20 years old and I would talke up a 'silly waitering job', just to be around people. I think that I might like that, now, if I had 20. Just one example. Just serve food and drinks to happy people, see them enjoy the evening, and banter around a bit. Get some positive energy. Postive energy I used to be blind to.

What I did the last 1.5 was similar to you; I sat at my parents place, working on my thesis project that isn't supposed to start yet next month. Even my father asked me now if I was 'going mad', focussing only on academics. An abusrd thing to suggest now, and not in the past, when I was truly mad. It is one of my worries.
But I am just happy I have something I am excited about, happy to work on, keep me engaged. And something I may be good at and may gain me money and respect, eventually. Academics is my escape, I guess. But maybe also a shell I can hide in so I don't have to change. I guess I needed that because of circumstances (second failed romance after 14 years).
I am back in university town since yesterday, I talked very briefly with a few students and did my exams. They have no idea what is going on in my mind.

At least be happy you are scared of being lonely. It may be your insurance against being lonely and being ok with it and then at age 40 waking up to the reality that you really aren't ok with being lonely and have wasted half your life.