Don't worry about the strength yet......it will come.....strength is built when days turn into weeks and weeks turn into months and months turn into years......2 weeks isn't long enough to gain 20lbs of fat and it isn't long enough to gain 20lbs of muscle. Your body was starved and depleted and you're restoring water and electrolytes and replenishing your glycogen stores....DON'T WORRY ABOUT A THING, it's all normal.
This isn't a scientific statement or anything, but with your height and frame size, you're still grossly underweight.......so, that's why the scale is moving without crazy amounts of calories.....you're probably not going to have to consciously crank it up until you get to about 200lbs or so (probably a normal, healthy weight for a guy your size)