It's not far off the norm at all. Loads of 20 year olds are awkward as hell, most of them far more than they realise, and plenty of them I would not consider to be adults in terms of their mental development. People mature at very different rates in different areas also, so try not to worry about it! Seeing yourself as "awkward", although I do understand what you mean, is also not really psychologically helpful. Try to get away from worring about what other people might be thinking of you - you can't read minds, and most people are far more wrapped up in their own issues to really care about the things that you might assume they would notice or perceive as "awkward".
Just do your thing, socialise often, don't worry about what other people think of you and know that again you're not far off the norm at all and in fact probably have a lot more self-awareness than a whole bunch of other 20 year olds who are running around thinking that they're ready to take on the world and blissfully unaware of how much more learning about themselves and the world around them they have to do. Apart from this I would suggest researching tools to manage your slight social anxiety - anxiety can itself become a barrier to your self-development if you allow it to affect your behaviour, and it will unavoidably affect your ability to think clearly in some situations. There is a lot of information out there though, and if you can break down the anxiety into physical and mental symptoms (increased heart rate and breathing, "what if everyone is judging me?" type thoughts) and then address these individually (with, say, breathing exercises, and methods to challenge your negative thoughts as they arise) then you will become not only more socially confident in a realm where you were never really in a ny physical danger, but also far more able to manage any truly frightening or difficult situation in your life ahead.
