Ok. That's a lot to take in, but I think I have.
Oh, I so wish that this weren't the 21st Century. I'm dying of curiosity about how old you are, but you really shouldn't post that information.
Why not? It's such a small piece of info. You don't know where he lives, if he is actually male, whether or not the age he might tell you he is real and so much more.
Birthdates are really sensitive information, not directly for kids, but kids grow up and all kinds of financial and medical records revolve around birthdates. It's entirely possible to get the year from one place and combine it with some "yesterday I got such-and-such for my birthday" from a different place.
I think "I'm between 9 and 12 years old" or something along those lines, especially if you're not exactly 10.5 :), would be okay.
Let me make it clear that I hate this world we live in. I'm with you in spirit.