I strongly suggest you add a tablespoonful of flax oil to your shakes.
It might help your nails alot, as well as the nerves. You have to have omega-3s in order to live and heal. (you won't taste it).

Try to use fresh fruit, as this is high in potassium. The whey is predigested so
you don't have to worry about protein failures. Some wheys have l-glutamine added and that is also good .

Bananas, strawberries, mango ( I like mango ones) are good and have alot to
offer. There are fruit sorbets by Edy's also, which make nice smoothies quickly. An ounce of boysenberry really works nicely with fresh strawberries!
I also do pineapple (canned in its own juice)/coconut milk to make a pina colada type. I typically use vanilla yogurt instead of milk. And thin with the fruit juice. I think you need to get some good fats into you, to repair. Your weight loss will allow you that luxury! Yogurt gives cultures and calcium for you better than milk. It is easier to digest too. (you can't taste it in the mix).

Some people cannot tolerate Splenda...so I would not use that yet. YOu are not looking to lose weight. Using fruit, no extra sugar should be necessary. I never have added sugar.