>>33514495 (OP)
>Would it be weird if I made a post in the group looking for friends around my age?
I don't think it'd be weird or bad. Just approach it casually - you came to convention, it was fun, you'd like to get friends and meet more people sharing such interests - that's it.
Now, people are suspicious and they may treat you as if you'd be weird/bad unless proven otherwise, but if you're genuine and don't have ulterior motives - you shouldn't be at fault there.
You should work on your socialization skills though. If people approach you themselves in a friendly fashion, it means you already have the awesome luck of pushing past one of the biggest obstacles - actually beginning contact and making first impression. Now you actually keep in touch, talk, share experiences. It may be tough, people may ignore your posts but that would be a different problem.
Out of curiosity - do you know why were you approached? Maybe some fun cosplay? Do share.