Told ya hehe
On the wrist thing - its "merely" your force output being higher then what your wrist can cope with. Your wrist will be your weak link.
Ring work - handstand pushups - prehaps pushups on the fist (id use a padded surface for knuckles if you dont want arthritis!).
Slight digression -
Its for this reason that id advocate using a palm heel when fighting barehanded. Once you really start learning to generate power the risk of smashing up your knuckles or hand becomes too great. Infact it should become 100%. Particularly when your targetting the head! A hard boney surface with a hard boney surface!
There arent ANY fighters i know of that dont risk this. I dont give a flip if there channeling chi or spent the last 10 years "conditioning". Eg boxers break there fists all the time in street fights. And the ones that dont modify what there doing - ie strike with less then 100% or body shot..
In the mean time your gonna have to scale your strikes a bit. Hit with less then 100% power, focus on form and choose your shot more. Sorry its that or have your wrist buckle! The wrist will strengthen over time in response to your striking....
Tell your MMA coach and if hes a knuckle head theyll tell you to keep blasting, give you a tonne of knuckle pushups on a hardsurface or similar. Essentially unpleasent training "because were hard we are!". If hes a smarter coach youll find him looking to, protect and actively strengthen your wrist and give you sound guidance to doing so.
Alot depends on whether youve got a Smart or Knuckle head coach
Maybe with the later its an idea to keep quiet and just get on with it - and strengthen in your own time
Yup the end of your shin, top of ankle should feel it - but will adapt - make sure your striking properly though...
Again watchout if your hurting too much - sounds like your a strong dude whos whacking with alot of power. Youll probably find at this stage your form is a bit raggedly and a good trainer will get you to ease off on the power alittle and attend to form more.
This form foundation pays off in the long run with greater top end performance (power and form under pressure) and fighter longevity!
Talk it over with your coach (unless hes a knuckle head) and other fighters....
Good luck dude!