Proper posture is important when squatting to eliminate. Feet flat on the surface - no balancing on your toes! If you cant quite get you feet onto the floor try some rolled up socks under your heels, with enough practice you will be a pro in no time. When your heals are firmly on the floor then all your muscles and tendons are pointing in the correct directions. Westerners are not accustomed to squatting so there is a body training curve to overcome, but once you have correct posture while squatting then the whole process of elimination becomes quite automatic with no straining and little waiting, at least I can vouch for in my case.