Hello Hooligan ... Great job done! The most important part are those brownie points!!
Agree that french seams would work, if you want the seam edge closed in.
Although, there is nothing wrong with the way you did them.
Not sure where you are in the province, but if you have a Len's Mill Store nearby, they have been advertising that they have the fabrics for gowns and all other PPE needs. So, a place for you to check.
You probably should check with her employer as to what fabric choices are acceptable to them, in lieu of their provided disposables. Better than getting into mass production and discovering that they have specific requirements ... or will not even allow home-sewns.
As for pattern re-sizing ...
I think the others have pointed out pretty much what I was thinking.
Are you wanting the different sizes to make for her colleagues?
Or just wanting to have a generic pattern to sell/giveaway to others?
If it is for her colleagues or others you know, you could always let them try one on and alter accordingly.
As already mentioned, these gowns are meant to be loose fitting for over other garments. It'll be important to keep in mind that loose fitting now, may become tight fitting, as we shift to warmer fall/winter wear.
Good Luck!