FEAR OF BEING MENTALLY UNHEALTHY?

Does anyone feel like alot of their anxiety actually comes from the core belief that there is somwthing wrong with them? And by something, I mean mental health issues?
Personally, I blame relational anxieties and failures through the years on a core belief I formed early childhood when I went to a kids camp and found it hard to make friends, and was a bit of a social outcast/loser due to being more introverted an shy. Unfortunately, instead of accepting this and having some self-compassion, I took on a core self criticism that I was 'bad' socially. This then started a vicious cycle where my lack of belief in my abilites and 'normalness' indeed led to social problems and anxieties.

This cycle came to an end when I became a Chirstian at about 23 yrs of age, for two reasons.
I was taught at the church I went to that I was now a 'new creation' and 'old things had passed away'. This somewheat unwittingly set me free from a lifetime of self criicism due to social difficulties and relational failures and anxiety. I was a completely different person! I also felt loved and that I could be myself, which helped my confidence.

Unfortunately, this all seemed to come to an end a few years after that, when I started to realise I still had issues with people, approval seeking etc. I also picked up a book which talked about how children of alcoholics had low self worht and neede to work through their wrong-beliefs they have carried into adulthood. Now, as my father was an alcoholic, I was instantly transported back to the belief that I am flawed in my perceptions and ways of being, purely due to the fact I had such an upbringing!

I now find that it is actually this core belief which causes me anxiety. If I could somehow actually believe that there is 'nothing wrong with me', then my anxiety will almost completely go away! I know this as my psych who I just started seeing managed to convince e of this, and the ensuing few days after this were 100% anxiety free!

So how do I convince myself of this permanently? How do I transform this core belief when a lot of the "evidence", ie. past relational failure, social anxiety, etc. as well as the fact I had a dodgy father, seem to tell me otherwise? I feel like I need to 'fix' me, but don't know what to fix!!
Can anyone else relate to this?

Is this the hardes thing to beleieve? That we are ACTUALLY normal???