I had RNY gastric bypass surgery and for the first month my meal volume was limited to 2 ounces per meal. That is almost nothing. With this minuscule amount of food, it is next to impossible to meet your protein daily requirements by food alone, so therefore you need to rely on supplements such as protein shakes. I found that if I met the fluid, vitamin and protein requirement, I had all the energy I needed.
In your case since you are very much on the go, you might need a little extra protein. So I guess I am saying don't stress on the meals, but rather put your focus on meeting your fluid, vitamin and protein goals.
If you are weak, it can be due to dehydration. If you are weak it can be due to an electrolyte deficiency (such as potassium and sodium). Without sufficient protein, your body will scavenge protein from other areas of your body, such as your muscles. Protein is extremely important after surgery as its job in the body is to build and maintain tissues including your body's major organs and skeletal muscles. Protein deficiency, when continued over a long period of time can cause a disease known as protein caloric malnutrition. Common symptoms are poor healing, fatigue, hair loss and muscle wasting. Immediate post op, protein promotes healing of the staple line and incisions.