Hey Stacy, if you have no luck finding one...you can take a 10ft piece of 1 inch webbing, tie both ends with water knot, make a figure 8 loop and have the person put his arms through it from the back and secure it a locker in the front. You can then adjust the water knot to a more snug fit and either cut off the extra webbing or tie it off so it does not get in the way. You can then run the rope through the front locker and tie normally into the harness.
I have a Medium/ small one I used while pregnant I'm looking to part with. I can sell it for 20$ + shipping. Otherwise, you could look into women outdoor/ climbing groups on Facebook. There are usually a good handful of women who have a harness for sale.