I guess this is my moment to shine.
It sounds like your body doesn't like booze my friend, so simply said, DON'T DRINK. (I read somewhere that hangovers are a genetic response, luckily I don't get them).
Anyways, I've been confronted with this situation plenty of times and must admit that at first, I didn't have a damn clue as to what to do, because it does feel awkward, all your friends are drunk and doing stupid things, girls are drunk, and since you're not stumbling around the bar/party walking into things, lets face it... you look like a stiff prick.
So what to do? Yeah, you can go around with fake drinks or water in red cups and in honesty, I think that's acceptible. I've done such things, besides, you go out partying for the night, you will get thirsty. So even though there's been times I've used the red-water-cup, I've never once lied about what I had to drink (I don't lie to people).
Also, I've done the nalgene with protein in it before, don't mix milk with it or it'll start smelling rancid after its warm for about an hour. There's something about carrying a protein drink around a party that gets everyone's attention, so be prepared to tell everyone that "I'm not drinking tonight" about 50 times, because people will be asking you left and right. Incidentally, this also means that plenty of girls will ask you what you have as well, and you have an instant conversation starter (don't use this as a crutch though).
Personal Dilemmas: What to do when you hit it off with a girl who just so happens to be smashed, and you are stone cold sober? I have a belief in that it's wrong to take advantage of a drunk girl. If I'm not just as drunk, I usually can't tell how drunk people are (it's a catch 22... weird). Here's why: when you end up getting "all tore up" you usually don't realize how drunk those around you are and people seem 'normal' when in reality they are smashed (as are you). When you go out SOBER you're going to realize everyone is an idiot, EVERYONE. So these are some tidbits of advice I can give if you like to meet lots of girls:
1) Drunk folks don't remember a lot of things. So if you get her phone number, odds are, she won't remember giving it to you (same goes for anything else she might give you), so that's when you 'advise' her that she write your name and number ON HER ARM! I know it sounds weird, but she'll wake up looking at it wondering who this mystery character is, and when you call, she'll be all about it.
2) Get a date. Believe it or not, these party hungry morsels of sexual desire actually want a guy to take them out, to do things with them, to treat them good. You figure that most 'hook-ups' in college happen only at parties and bars when people are drunk... while this is fun at first, girls will move on and want something a little different (it happens sooner than you think, after all, why would they keep going out to big parties, it's not always "JUST TO DANCE" it's to find a guy, thanks mother nature).
3) For the love of god, don't be centered on ONE thing in life, if you don't know this by now, get some different hobbies, play some intramurals, have lots of things to do. Start listening to country music, most chicks love it (as do I, but I've always liked it) or another thing you don't normally listen to, LEARN and KNOW about lots of things, this way you'll always be able to keep conversations rolling.
4) Practice the Flirt. Girls LOVE to flirt, girls HATE it when they don't get what they want. Learn to be subtle and flirt your ass off, you'll only get better with practice.
5) FORGET THE FACT THAT YOU AREN'T DRINKING. fuckit, go out and have fun. You'll be the only fool around to be 'on top of his game' and not slurring his speach. Use this to your advantage.
6) SMILE if you don't look happy with yourself, why would a girl be happy with you? Make sense?
7) Don't be desperate, don't rely on gimmicks (such as the protein bottle, but really, it does get lots of attention, don't rely on it though). Girls can smell desperation from a mile away, don't smell desperate.
8) Never cock-block me! That'd be rude to do since I tried to help you out.
There's lots of things to do other than drink, and eventually, you'll get used to not drinking and still be able to have lots of fun. It just takes some 'practice' and getting used to.
Now I'm off to watch football all day, in HD, good luck bro.