Having trouble throwing with power. I,m throwing more outward than downward if that makes any sense any thoughts.thanks
Maybe you know all of this already, maybe not, but this is a public forum so I'll answer as if any kohai student asked me this. Shihonage is one of my favorites, maybe because I am short. If you are much taller than uke, it will help to get in really good shape so that your core is strong enough to make the squatting pivot movement comfortable and easy. If you lift uke's arm overhead, or bend over instead of squatting to get under uke's arm, you will lose aiki, and power.
You can also try lifting the elbow of the arm uke gives you, during the tenkan movement, by making the first part of ushirotori undo movement of your arms. Draw in a deep breath. (I'm currently working on breath/kokyu power) This movement will lift uke's center and force uke's chest out and head back. If you do this fully, your arm will end up underneath uke's arm, and with aiki, this force will end up partly supporting uke. If you release uke in this situation, uke will fall, straight down, without need to apply any additional power to the throw.
To apply additional power, as you pivot and "wind up" uke's arm, imagine it is a bokken, bringing it up in front of your face, keeping your spine plumb, and execute a shomenuchi cut movement with uke's arm-bokken. Release the drawn up breath. This movement can force uke to take a very high breakfall if you are underneath uke's upper body weight as I have described above, with very little additional power when aiki. It's easier to throw uke shihonage for breakfalls as suwari waza. It's all about raising uke's center/fulcrum and then dropping it suddenly. It only seems like a power throw. Adding power just spins uke's body in midair around his center of gravity.