Scared of going out iin?

So it took me ages to actually go out clubbing. I'm an anxious shy girl with little friends so when my cousin asked me out round town I said yes had a great time and felt someone normal and accepted. I've done it a few times since then. Can't say it's my thing but after a few times of doing it all the other girls stay out late and mix drinks and just drink anything. I only really like cider and larger and I usually drink shandies and go home earlier cause of my work commitments but what must they think? That I'm no fun?
I think I overthink it but I don't really like much drink. Bitter shandy is nice but it's boring isn't it? I feel it is. I get drunk etc. Tomorrow though I've been invited out and because I don't do much to socialise I go just so my parents don't worry so much but I have work all day the next day so I was planning on not drinking much and leaving earlier like not getting fully drunk. Cause usually I can get up for work and sleep the next afternoon but not on Thursday. They all smoke as well and talk about sex and that I've never had a boyfriend so
I'm all shy and never know what to say.
It's awkward I just wish I fitted in.
I'm so worried about going with them tomorrow.
What should I do? Any tips?