How to be confident and not awkward

Hi please help. I've been told I'm a really pretty girl & I don't have a problem getting guys to talk to me or getting their attention, but I have a problem with them staying after the first few times we hangout. I keep trying to convince myself that it's because they aren't the right ones for me etc but I really think I have a problem with socializing and confidence. I'm really fun, loud, and sure of myself when I'm drunk or when I'm around people I'm really comfortable with or people I'm meeting for the first time, but it's really really really hard for me to be myself or have  conversation with people (guys and girls) that I kinda know but still aren't comfortable around if that makes sense?? Like the first time I meet someone I can talk for hours about anything and I feel really confident and that I have a lot of valuable things to say,  but the next few times I hangout with them I find myself being very quiet and reserved and not myself and honestly I think people may think I'm a bitch at times because I usually just don't know what to say or respond bc I'm scared that I'll be judged for what I say or that I'll say something annoying so I just laugh awkwardly and the conversation just dies off. I just want advice on how to be confident and fun and interesting all of the time, not just when I'm drunk or comfortable so people actually want to keep coming around me. I hope I'm explaining this well enough but BASICALLY give me tips on how to not be awkward plz!! I'm curious to see how different people handle different situations! Thanks :)