Figuring your draw up with a formula doesn't always work that well either. It works for some, but not everyone. And seems to be less accurate with small framed archers and women. It doesn't work for me at all. Your draw length can change from bow to bow or if you switch releases. A formula might get you close, but in most cases it won't nail it.

Again, from looking at that picture I don't think you should mess with it, you might end up going too long and doing more harm than good. And there is no way anyone on here can look at the pic and say you are 1/2 an inch or an too short. I would have to watch you shoot multiple times from different angles to tell that.

You need to practice more and be confident with your set up, not mess with it and doubt that it works. I say that from experiance, I am a tinker a holic when it comes to my bow. Maybe in a few years when you are a more accomplished archer and decide to get a new bow you can work on getting your draw length more precise, but what you have now is plenty good. I have seen guys win indoor spots with worse form.

Paul