Your snakes weight would be helpful to know. Length is not a great indicator. For one most people have a really hard time getting an accurate measurement. Another problem is that without weight its hard to tell if the snake is at a healthy weight. From where I am sitting that snake looks underweight. I would be feeding 1 adult mouse every 5 days at least. Ass for the pooping issue. Your snake will poop when it needs to poop. Unless you see a bulge near the vent I wouldn't worry about it.