Well, no because...
1) You're body might not even be fully developed to handle any type of sex I would not want to be embarresed infront of my girlfriend if something did not function properly.
2) I personally would find the image of someone 14 years of age recieving a blow job very well, not disturbing but awkward but of course that is my opinion nothing to do with you.
3) Would you really really want the risk of catching a disease at that age?
However it is your choice.