Duncan,
Pretty good for just 6 months!! Here is what I see that you might want to think about or try.
Your bow arm is well below being 90 degrees to your torso/spine. That is the only problem you have regarding your shoulder. Your bow shoulder is OK but would be better IF you lift the bow arm to 90 degrees. Draw on the horizon THEN bend at the waist if shooting at a target on the ground. If possible, try to set your target so the center of it is at your shoulder level. This will help you learn the feel of setting that 90 degrees, and achieving the archer's "T".
You start the lift to draw with your bow hand relatively closed on the bow grip, then you open it -- sticking your bow hand fingers out straight for some reason. This adds tension to your bow forearm. Then before release, you close the hand again. Why all the movement? Just lay your fingers on the back of the grip before you lift to draw and leave them there.
Last, watch your head as you reach anchor. See all the movement? When ready to shoot, lift your head to look at the target and then don't move it again. Pull the string to your face and set anchor with your string hand and not by moving your head around to "cuddle up" to the string.
Reducing unnecessary motion will simplify your shot, give you fewer things to "think" about and help reduce muscle tension that is not needed or wanted in the shot.
Again pretty good start, now try to refine and not use any muscle not actually needed for the shot.
Arne