The way to fix this is to fix your form. And the best way to fix your form is to work the separate components of your form by focusing on those aspects and not worrying about hitting anything. IOW--you need to forget about shooting targets and hitting things for about 6 weeks and go pound a blind bale.
I know that's not very fun, or appealing. But if you really want to improve its the way its done.
Confident execution of your shot only comes through good form. And good form is a function of seven or eight separate but interrelated things--grip, stance, back tension, string hand placement, follow through etc.
Your shooting is inconsistent because your form is not consistent. And you don't fix something like this by practicing the same thing. You need to go back to the basics and work on the components of your form until they come together and you can repeat the actions with perfection.
Archery, like all shooting sports, is a DISCIPLINE. If you want to get good at it you need to work on form. Just like a baseball player works on his throwing form or a golfer works on his swing... form, form, form.
It will set you free. But its a pain in the butt to pound a blind bale for 6 weeks every day too. Do you have the discipline it takes?