Let's face it, fitting is always difficult, particularly on yourself!
Why don't you put everything on your stand shaped to your measurements and try to fit it on it? I avoid many problems in the fittings by doing so. I discovered a tailor rule to find the depth of the armhole for example, it is very efficient and it is always in the right place.
The link between the armhole and the waist is always important for a good fit but I'm sure you know that. Well, I tried to be helpful but really, save time, it's so frustrating when everything goes wrong... So keep up!!!We're on your side ;)
A académie of costume would be the appropriate thing for your problem ;)))