I am all for low carb but Dr. Bernstein’s low carb is an extreme in my point of view. I think you can safely up your carbs and still maintain a great BG. 36-40 grams per day is pretty low. You might try eating around 60 grams give or take then hopefully you can find a happy medium so that you won’t lose weight but won’t put too much back on.
I would use one of the web-based businesses that let you formulate your own meal replacement and supplement shake powders. My personal favorite is Protein Factory (www.proteinfactory.com).
They have a unique ordering system that lets you add the specific components you want (vitamins, amino acids, every kind of protein from bovine plasma to egg to many kinds of whey). I use their whey isolate, as it is pure protein with no carbs, no fat, and no cholesterol. You can also pick the sweetener you want- I use stevia but all of them are available. They have a large selection of flavorings too (cookies and cream is my #1). I have no affiliation with this company other than being a satisfied customer.
I find it can often be easier to get extra calories if you can drink them as opposed to cooking a chicken or something.