In my case it was kind of funny because even if I was actually over 13 when I joined here, I used to fake my birthday and my year of birth on the internet back then because I was really suspicious of the internet at that time. xD But when I saw that it didn't work that way, I was just like oh well, then I'll put my real birthday in there.
I wasn't sure so I looked back to my old account to see how long I've been here...so I joined at the end of January in 2009, and my birthday is on the first of January so I would of been 15. Looks like I let it sit around for several months before doing anything with it as well XD I don't think I really even used it regularly till I was 16. I wouldn't mind the age limit being higher (maybe 14/15), but I know that I made some really good friends when I was on here that were 13, and they were not only talented, but were very kind and sweet and loved art. I think that the limit should stay where it is.
I joined at the age of 10 on a previous account (mainly so I could watch a particular artist). Then I made a new account (this one) at age 11 because I was embarrassed by my actions on that account and I also didn't like that it had numbers in the username. So only recently I became legal to have an account. (I thought about turning myself in a few times)