who's been giving you a tough time? there's a line between showing concern and being totally unsupportive. sounds like these ppl are the latter. even concern can be shown in an understanding way and shouldn't be made to make you feel like they're attacking you for your choices.
everyone has to live their own life, and make their own decisions. do what makes you happy.
:( i'm sorry that people are flipping out because you're engaged.
That's the same thing that happened to me when I got married. People still give me [censored], and I'm 3 years older than you! But don't worry. The same people that talked crap when I was engaged are married now with kids. They've given up all of their dreams because they got pregnant.
As long as you're happy that's all that matters. Age is of no consequence. I'm glad that you've found the person that makes you happy and that you guys are getting married.
Anyone who isn't happy that you're happy aren't real friends.