How fast should i be bowling at 13 if i want to become a really good fast bowler (cricket)?

If u can move the ball and have some subtle variations then even 130-135kmph would be fine. you' are shaping up quite well for your age thats not bad at all. To ball faster u just need to get the perfect rhythm going. Make sure ur run up isn't too long or too short. Time ur jump well if u have a side-on action.