Hi Tom,
It sounds like you have had a real collapse in confidence over the last year, did you used to be confident and have no troubles interacting with people?
One thing I have realised with myself and I know other people have expressed similar feelings on another forum is that once you have acted all anxious in a situation, that alone can start off a fear of similar interactions of speaking. For instance I once had a presentation which just went so horribly wrong - I was shaking, my voice went trembly and my voice just went. I have had a terrible fear ever since of public speaking, one of the main reasons is because I fear a repeat - I have no confidence that I can successfully do public speaking and I am so fearful of a repeat where I just go to pieces in front of everyone that this is just my ultimate fear and its too much for me to handle.
I can only talk about my own experience and my own beliefs of what I think is wrong - and if you don't agree with what I say - that is totally understandable because SA is unique to each person I believe - but I think you sound like you have developed some fear of people seeing you being anxious - and you believe if people see this, they will judge you negatively and as being weird? I suffer the same thing which I am currently in the last week or so am working on desensitising - to not fear being anxious - to not fear people seeing me anxious when I am interacting with them - because I must admit I am scared to death of people seeing me struggle with my confidence - like my voice going, or me shaking, or me swallowing deeply as I am talking - I just have this huge fear that people are thinking I am so weird and not normal. So I am trying to desensitise this.
But there is surely something else that is causing your anxiety? What is your self image of yourself? Do you like how you look, do you like your personality, do you like your confidence, do you like your intelligence? Maybe if you recognise that you don't like something about yourself to quite some extent - maybe that is also a real factor in what is causing you to be anxious around people - as you don't want people to see your insecurities.
Anyway, if what I say sounds nonsense just ignore it, I don't for one minute think I know other people's problems and how other people suffer, but I do know my own problems and making really good progress - so it may be of some use to you.