You are not alone in your experience. You sound "stuck". I've been there, suffered from depression for a while and went through some of that in a big way.

However, I believe your self-diagnosis of narcissism is off the mark. My experience with narcissists - and I have known several - has been that they are self centered, although not necessarily in the same way.

I know one person who is always doing things for other people and giving money and things away - food, furniture, rides, whatever anyone might need. You might think this person is a saint. Not true. Someone who is constantly talking about all they do for others and how much they themselves suffer and asks why no one does any thing for them and needs constant validation from everyone around them... totally self absorbed.

Another person uses drugs (not narcotics, but is constantly high) and is an older man, set in his ways, 'stuck' in everything in his life; always broke, so self-concerned and egocentric that he looks in a mirror and sees himself as he was 25 years ago and doesn't understand why 30-yr-old women don't find him attractive.

If any therapists have mentioned narcissism to you, and I doubt they would, then ask them why.

It isn't only a trait of narcissism - You can be Very self absorbed through say Autism but wouldn't really be classed as narcissist. You have to actively be gaslighting people / probably devaluing them / slowly eroding their confidence / Making people question who they are on a fundatmental level / lying to people a lot / treating them as literal objects in a chessboard ... !!

Please do not go thinking you are narcissist unless you display most of what I mentioned above as that could be confusing for you .. (it is a specific personality disorder alone as well as a component of some other states) !!

Unless you display a few of these traits you are likely not.

You can be very withdrawn and still not self absorbed focussing externally !

Overthinking is a very unhelpful word for you I feel ... look at mindfulness if you haven't

Possibly look at CBT .. possibly look at therpay .. if you haven't already... much love.

Holy bleep I relate to this too much, have just never seen it put into words.

I was going to answer this but we have the best weather this year and I`m off to the pub.

What's the word for doesn't think it through closely enough... I might be that.

I have extreme radical ideas I keep in my head and to my self because most people can't follow the logic to them anyway.

Me too. I try to put myself in positions where I can be less self-aware and just feel something. Of course you have to be careful and make sure you are in the appropriate physical and mental place to turn off those higher cognitive powers. One can be addicted to consciousness too.

Somehow, someway your first paragraph reminds me of this:
[ideapod.com]

The rest reminds me of a classic introvert.

I fall into that quite a bit, but I'm enough of an extravert that every so often I have to get out and be with other people. Every few days? Once a week? It depends. I tend to be solsipsistic as well, but I try to fight it.