Hi struggling - I too was like you for years and years, and used to think people must actually feel repulsed by me, as I was soo ugly and socially inept, could never 'banter' with the ease that everyone else did, laughed too loudly at a not-funny joke, or not loudly enough at a funny one. Just felt clumsy, ugly and SO self-conscious. And, yes, the overriding emotion was SHAME. This feeling probably went on till my late twenties/early thirties when I met a wonderful, kind, sensitive, good man, got married and had babies, and had other people to worry about all the time rather than myself!
Now I look back on those times and think, bloody hell, what on EARTH was I worrying about? I was gorgeous! A bit gauche, a bit awkward, perhaps, a bit over-sensitive (I am another sensitive type that can pick up on everyone's feelings and moods) - yes, but nothing worse or more hideous than that.
If I were to speak to my younger self now, I'd tell her very, very gently to get a grip, and realise that most people actually aren't that interested in enough in you to give you more than a second's thought - they've got their own crap going on! And I'd also tell her to stop spending all her money on trying to make herself look right to 'fit in', as well as on all that booze to give her confidence/drown out her feelings (another fellow 'party girl' too), and instead invest in some really good counselling, to get some perspective on why she feels this way and how to learn how to heal. (mine was rooted in an early trauma and cold, emotionally distant parents, but that's another story..).
I second all the posters saying that they bet you are actually quite gorgeous and just being incredibly hard on yourself because of these feelings. Don't believe the nasty voice in your head telling you all this crap, it is rubbish! You may never feel super confident in your own skin (I still don't) but I can definitely 'fake till I make it' now, and I genuinely worry more now about what I think of other people, than what they think of me.