Does anyone else feel comfortable by themselves but isolated at the same time?

I find it sad that you were conditioned to suppress your feelings, and can only imagine how difficult it must now be to 'unlearn' that conditioning. 

Me similarly (see below).

I've grown up feeling like my feelings are all wrong and that I must react in a certain way, therefore there's shame surrounding it. Especially as often admitting feeling sad about something has caused issues in some way.

I was trained conditioned etc not to admit I feel lonely (or anything else for that matter, we should show no fear or pain i.e. regimental). I'm starting to allow myself to admit such things to myself(and even others) but is still pretty alien to me / 'unacceptable behaviour ' / signs of weakness 

You shouldn't feel embarrassed to admit that if that is how you feel.

Yes... and also no.

Sometimes I can be perfectly content with my own company, but then I'll go through phases when I don't and will feel desperately lonely, despite having an adult child who lives with me.

I've always been a bit funny with this. I can cope with doing things on my own; I've been to concerts on my own and I do most things alone because it's more hassle asking someone else.

Yet it often feels more comfortable having company and less isolating. And safer. But I'm embarrassed to admit that.

Oh im also not quite an adult. I thought "As an autistic adult" was just referring to them being an adult and not wanting adults to answer 

I'm not quite an adult.....yet but I do suffer badly from loneliness and isolation. I have no friends I have a pretty big family but I tend to stay on my own in my room because I don't feel like I fit in anywhere or with anyone else. I find people really difficult and confusing. I spend a lot of my time trying to fit in but I can never manage to and still feel lonely and isolated.

Only every moment of my life. I prefer to be alone yet when im in public and nobody cares about me then I wish I had friends (even though friends are hard)