Is it normal to constantly be afraid of people judging you?

I'm like this too, I don't really know why, my dad was an asshole, well, he was more than just an asshole, he always treated me like shit so maybe that's where I got it, I'm not sure.
Then again I never used to be like that, I used to go out skating and go to gigs with people I knew, and with people I just met, then gradually I just changed, looking back though I think I've always had an element of anxiety, I could have mates and joke around with people fine but whenever anyone showed any feelings or attraction towards me then I'd get a bit anxious.
Towards the end of high school I started suffering from social anxiety, everything I left the house I would feel like everyone was looking and judging me, I even dreaded a trip to the shops.
There was a period of a month when I didn't leave the house except when I was asked to get something from the corner shop.
I'm still overcoming this but I'm nowhere near how I was and it all came from a piece of advice anime7gave on a post ( and if you read this thank you) act confident, your mind will follow, walk with purpose, even if you don't feel it walk with strong confident strides, it actually does work, Do things you wouldn't normally do even tiny things like using a manned checkout instead of a self service kiosk, it May sound hard to do but just act confident and your mind really will catch up.

But like I said, I've improved massively but I'm still working on myself, my problem now is mire mental, I can talk and laugh with New people but I will walk away with insecurities like " they hate me" or that I came across as an idiot, so it can take a while but you'll get there.

You're right, people are dogs!!! Not really, I know what you mean, there's a Lot of sub-communication that goes on; if people sense a lack of confidence, they respond in a way which tends to reinforce that - like a vicious circle (..of wild dogs).
It also really sucks that you are still carrying the high school experiences around with you. Some stuff seems to get in so deep that's its very hard to get rid of. And it had no right to even be there in the first place. I'm sure it's something you try and avoid thinking about, but it's still affecting your self-image and behaviour.

And that deep fear of humiliation; or that you are being judged is just not based on reality.... It's hard to switch off I know.

There are ways to get yourself feeling in a confident state of mind. Different visualisation things etc. with the end goal being to evoke a confident state and improve the way you think about yourself. It involves playing with the mental images you have of yourself (which are probably not accurate and definitely need to be more helpful) I'd recommend giving this stuff a decent crack. It's something that you may have to continually work on.

Confidence is not real; it's not necessarily justified and it can be faked!! To 'fake' it you kind of have to believe it though (which isn't all that hard, you just have to force yourself to change the way you think).

Also, the king is right; you can definitely trick your brain into feeling confident just by carrying yourself as if you are already feeling that way.

So stand tall, work on your self image and soon you'll be going to the manned checkouts purely out of laziness.

It's all in your head, just let go of those irrational, self-demeaning thoughts.

Hey, I was a late bloomer and I got my period and got boobs much later than many people in my school. I was afraid people thought I was different and felt scared my friends judged me. I knew I would be a late bloomer and I knew I would only hit puberty when I'm around 14. I realized people don't really give a shit about it. If people don't accept you for you, then you shouldn't talk to them in the first place.