Hello there and welcome back to the forums, Michela! It's nice to see old fans returning to the whole obsession! Was it the release of B/W that sparked up your interest in Pokemon once again or was it another thing, I suppose? What ever the reason may be though I'm really happy that your back and hopefully you will get yourself reacquainted with your friends here. :D
I think age really doesn't matter if you're a fan of something even if it's kind of childish like Pokemon. I mean as long as you have fun with it there's nothing wrong with that, just ignore the people teasing you or whatnot they just have nothing to do that is why they make fun of you. But yeah, I'm quite sad for those kind of people. xD
Anyway, PC is pretty much the same board that you've registered to, the only difference are the new boards, new members, new staff, new rules which I'm quite sure that you will eventually get used to, but if you need assistance, Megan and I are here to help you out so don't hesitate to approach us if you need a tour! :p
Give the rules a reread most especially the recently updated signature rules, that will keep you away from most troubles that you really might not want to get into!
Have a wonderful time and hopefully you won't leave us hanging around once again. teehee;