How to be more confident (or care less?!)

[FuggyPidding]

In my forties, wife/mum, decent job, nice friends, financially secure etc etc, and I'm happy- but oh how I wish I had more confidence. I'm quite quiet and very self conscious, I really care what people think about me and I think it's that what is knocking my confidence. I worry about what I look like (to other people), how I sound when I talk, my mannerisms, my behaviour etc. I'm scared of sounding silly or looking stupid, so much so it stops me doing things. For example, I'm really reluctant to answer the phone at work in case I don't know how to deal with the enquiry - sounds weird I know!
I know people who are full of confidence and don't seem to care what people think of them and it actually seems really liberating! My colleague the other day told me how she spilt her coffee all over herself, the server, the table etc in the middle of a busy cafe. She had no reason to tell me (I wouldn't have known) but she was just laughing at herself/ the situation, saying she was mortified but could see the funny side now. If that happened to me, I would have been so embarrassed and never mentioned it again! Her response was liberating, I wish I was more like that- but how?
Are there any books I could read on how to improve my confidence? Or stop over thinking? Or any tips would be appreciated. Thank you.

I've just listened to 'The Six Pillars of Self Esteem' book on YouTube and it was really great.
There's also 'The Subtle Art of Not Giving a F*ck' which I thought was quite good actually. There's also that book on introverts.. is it called Quiet?
And look at Kegan's theory of adult development.

Most helpful for me has been learning to see the good sides of my 'bad' qualities. For example, self-consciousness can easily become self-awareness. Quietness can become calmness. Tentativeness can be thoughtfulness. It's all to do with accepting and appreciating who you are. I'm never going to be an exuberant personality. I can accept that now and I don't have to be anyone but myself.
I also made myself an emotions worksheet to work through feelings of embarrassment or shame. I found that lots of reading and writing about my shyness helped. There will be some good TED talks. Do some courses (I took up singing and have done public speaking training to challenge myself). I've finally reached a place where I care a hell of a lot less what people think of me. In fact, going against the grain and not giving a fuck becomes a kind of subversion of the status quo and my own fear.
Counselling has helped too. And mindfulness meditation. Also anything that takes you out of your comfort zone.
I now get described as 'Calm and confident' rather than quiet and shy, and I think a lot of my awkwardness has gone as I feel more happy in my own skin.
Sorry not sure if any of that helps.

My confidence (or lack there of) was linked to my low self esteem. I found Sorensen's breaking the chain of low self esteem did wonders for my confidence.

I'm very much like this with lots of imposter syndrome to add to the mix. I swing between thinking I'm just useless, that I worry too much and probably need to see a GP about anxiety or more recently starting to think that I may have many signs of ADHD. What I don't have is any solutions or answers for you, sadly.

Thanks for your replies.
I'll look up those books.
I am a worrier/ over thinker and anxiety does play a part.
I do realise I'm not that important/ special and no one really cares what I look/ sound like - I'm just so self conscious.