Ganglion cryst please help!!?

[Don'tLookAtMe]

I can't remember when it appeared but I first began to notice a bump in my arm when I was 12. Than my mum told me it was a ganglion. I've researched a fair bit on them and to be honest, I'm a little worried. It is on the back of my wrist, just where it curves to meet my hand and about 2cm long. I don't think it has grown any smaller/larger in the past two years, and it hasn't caused any pain but I heard that pain can come later? Will it grow any bigger/smaller? I can't afford to get rid of it, so I really want to know if there is a possibily of it going away naturally? (please do not suggest whacking it with a book)

thanks