I apologise in advance for the long post, and if by chance you're just pulling one over as some are saying, then maybe someone else can use this advice lol.
Perhaps I could chime in and give you a bit of advice that may be more helpful than the "you're doing it wrong" advice you've been given. Firstly, there is nothing wrong with what you want to wear. There are those who will go on endlessly about faux pas and what not to do (and indeed, there are certain rules to follow), but what matters most in a general sense is how you feel and the effort you put in. You want to be comfortable, but you should always dress for the event. If your comment about people wearing suits to most events in your circle and sticking out is true, then it would be silly to wear a suit to these events. For parties, semi-formal gatherings, and that sort of thing, your outfit is fine. In North America especially, people understand rules, but generally not how to put them into practice. You can follow all the major rules and still look like a slob, while you can also follow none of the rules, and look amazing.
At home, people are very fashion conscious, but always very conscious of function. If you're going to wear a short sleeve button-up because you get hot that would make complete sense, but put effort into ensuring you get a fitted cut, and that your color combinations work well together. There is no reason what you want to wear cannot be fashionable, so long as you put effort into whatever it is you WANT to wear. Would I wear a clip-on? No, but that is because I know how to tie a tie and I'm not bothered by it. Do what works for you. It's silly, however, to look for a really "great" looking clip-on. They are sold at places like Wal-Mart, La Chateau, and Sears for good reason. Reputable designers do not make clip-on ties, so accept that you will have to settle. Though, to be honest, you could be served just as well wearing no tie at all.
Finally: When attending an event like a wedding, just put effort into your outfit. You are a guest, present yourself as such. Weddings are not opportunities for you to make a bold statement or push anti-conformity fashion choices into the spot light, it's about two people that invited you to their event. That said, you can wear what you want to wear, but wear it well. Don't pick something just because it's comfortable, or just because you don't want to put effort in. Put effort in, or don't go. Weddings are not about you, so dress as the occasion calls.
Here are some pictures that can give you examples of dressing how you like, but wearing it well, all wedding appropriate:
And finally, if you ever do want a suit as an option (something I would always recommend) then this suit is the only one you'll ever need, and unless you lose or gain significant weight, it may very well last you the rest of your life at a wear or two per year:
Just remember, it is not a list of rules that make your outfit, it is the effort you put in. Wear whatever you like, but for events like a wedding, put effort in to show you care. I promise, even in a short-sleeve and a clip-on, you'll look great.