You've really got the wrong "friends" and need to straighten them out. You can't let others define you. If you let them do that you'll never be you. So I'd ask, do you suffer from anxiety? Or depression? Do you suffer from general insecurity? And why would it bother you, at this day and age, if people think you're gay? So what? What's wrong with being gay? You're clearly not, or at least say you're clearly not, or is it not so clear? Do you have a bias against gays and that's why it bothers you? If you're in your 30s, as you say you are, because you kind of sound younger than that, you should be well past the age when what others think has that much impact on us. By then both you and your friends should have pretty settled personalities and should know one another so well that everyone knows what each is like. Is it possible you're younger than that? Just asking, because that would explain some of this. But anyway, if you don't like drinking, don't. Nobody's forcing you. If you're hanging with people who define their fun by drinking too much and you just don't like that, get different friends. If you're that susceptible to peer pressure, what's going on in your life that makes you care that much? And if you're in your 30s, you're not looking for girls anymore, you're looking for women. I don't just say that because women don't like being referred to as girls, it's also because women aren't looking for the same things that teenage girls are. The one you're going to meet probably isn't hanging out with your friends, she's probably a stranger who doesn't know you and you don't know her and won't until you meet her, so she's not around to hear anything anyone else is saying about you. So, to the core of your post, you're very insecure, but we don't know why. You might. You can work on that and if you can't do it alone you might consider talking to a therapist to work this out. I grew up with people who couldn't have fun other than smoking pot, but by my 30s I'd stopped and most of them had too and if they wanted to get high and I didn't that was fine with both of us. If your "friends" are that immature, well, you can't change them but you can change friends. Nobody forced you to drink too much at those weddings, that was your choice. If you don't see that, again, you have an insecurity problem which is really an anxiety problem and you want to get on top of if before it gets chronic. I know it's hard to see, but others really aren't that concerned about this stuff. What they most want is your personality, your company, your conversation, your insight. If the folks in your group are still acting like frat boys in their 30s, they're not worth your valuable time. Peace.
I see you mentioned Buddhism. Do you meditate or have you tried meditation? It might help (though it takes a few months, as the changes we seek take time.)
There are apps one can download onto a cell phone. One is "Stop, Breathe, and Think". Another is "Headspace." There are others.
Aim for a short period of time, like one minute, then slowly expand to longer as you are comfortable.
Or, alternatively, one can do meditative motion, such as qi-gong, or Tai-Chi, or Therapeutic Yoga.
The idea is this slowly calms the mind, one becomes more accepting of who one is, and no longer as swayed by opinions of others. (Secondary effects are others sense you have become more calm and at peace, which is attractive. Women notice and are attracted.)
Keep respecting yourself and find better people to hang out with, for one. I mean, I told my son what I'll tell you; women are attracted to men who respect themselves & don't let people force them into doing things they don't want to. I'm not saying all women are attracted to this type of man, but the smart and good ones are. But, as long as you let people bother you, they will. Just let them see that you don't care about what they call you. Quit letting these things get to u or you'll never be chilled enough to go on a date when it happens. You gotta overlook people like that and be calm and show you aren't bothered by what people are saying and thinking or people will consider that you really are gay. Harder said than done, I know. You're probably tired of being lonely or want to settle down with someone soon because you're not getting any younger. If anyone feels I'm not giving him good advice, please, by all means, especially if you have had experiences similar to his or work in the mental health field, call me out on it. I only put information based on my experience with people throughout my 34 years of life.
I keep a wine spritzer on hand at parties. They can have as little wine in as you wish, but they keep people from pushing you to conform. Staying sober gives you the opportunity to have good conversation with interesting people - their likes and dislikes and relationships.
I read your question carefully, don't give a damn about others' brother, do whatever you like, and do it in your comfort zone.
If you always think about what people might think after doing this kind of behavior, then just stop thinking it's normal to do things in your way.
You just need to take care, that your action doesn't hurt them.
Don't get forced by other words, and by their thoughts, you know what you are, trust yourself more than anyone.