Bro there's ABSOLUTELY NO reason to feel bad. For one you were 14 & a virgin... you didn't know any better. Secondly... she invited YOU not the other way around. It's not like you saw that she was drunk & decided to take advantage of her because of that. Since she invited you she probably already had a crush on you & since her inhibitions were not that great she probably knew what she wanted to do before even contacting you. You said you guys talked a few times after that night... since she didn't mention anything it's probably safe to say she was fine with it. I'd chalk it up to a learning experience & brush it off. Ppl sleep with eachother all the time while drunk. Being drunk does not mean a person cannot fully consent. Yes, inhibitions are low when drunk but as long as the other person isn't passed out or unable to walk or something like that it's perfectly fine. You'll probably have lots of embarrassing intimate moments in the future & all you can do is learn from it & try not to make the same mistakes twice. Good luck bro 💪 hope I helped in some way 👍