The obvious question to ask is, what are you calling your wrist? Is the string actually hitting your wrist or several inches further up on your forearm? If it's actually hitting your wrist, then the culprit is probably string/cable creep and you need to have the bow pressed down and get the rigging twisted up. Check your axle to axle length and brace height against the factory specs for your bow. If the brace is more than a half inch lower than it's supposed to be or the a-to-a length more than an inch longer than it's supposed to be, take the bow to the shop.

If the string is raking your forearm, that's when you think more about form and/or draw length issues.