@micromacro I found this
article from 2014 about F-Stop gear designing a camera backpack for women. It describes all the issues you mentioned and their design solutions for them. It was a
Kickstarter idea, and is now a product -
Kashmir Backpack.
LoweAlpine has for decades made a complete line of trekking backpacks specifically
designed for the woman's body. These have internal frames, are highly customized for women, especially as to torso length and where the bag rests on the lower back, and as to the separation between the straps at the shoulders and their different shape to accommodate a woman's breasts. I know this because my daughters have used their women's outdoor gear for years as Scouting Venturers and outdoors women.
Since LoweAlpine also
makes made carrying gear for photographers* you might call them or dig into the website - at the very least one of their day packs might be adaptable.
* EDIT: Actually the camera line LowePro was spun out in the late 90's during the stock market nuttiness. The outdoor gear company was bought by an Italian firm, then passed through a venture capital outfit, and was taken over by a British outdoor sportswear company after the financial crisis. IIRC LowePro is much less sensitive to women's bodies. Greg Lowe was really forward thinking - he designed his first women's gear in 1970.