All monks get proficiency with all saves at 14th, so giving Constitution saving throw proficiency again at 17th makes no sense. I'd drop that part and switch it to refresh on a short or long rest. It's situational at best anyways as you shouldn't be dropping to 0 that often.
Also, an extra attack as a bonus action is only useful if your weapon attack is more powerful than your unarmed strike. Since both use the same damage at higher levels, then it'd only be useful if you have a magic weapon and it'd usually only be a +1 bonus over what Martial Arts already gives you every round. Seems kind of weak.