look, I am a heavyweight myself, I understand. That still doesn't mean that a .22LR from a 2 inch barrel is going to perform miracles.
Jam it in your cleavage if you have to, just find a way to carry something bigger.
check out a fanny pack swung so it is actually over the FANNY. Yes, this may add an extra second or two as you must twist the fanny pack back around to a reachable position, but I think it is worth it
What about thunderwear? Belly bands, where you access the firearm by opening the buttons on your shirt and reaching in?
what about pocket carry?
carry in the back pocket of jeans using a pocket holster
Wear skirts not pants? When my mom made my sister's wedding dress, she put unobtrusive pockets it it, so you can put pockets ANYWERE
Confident shirt from Kramer?
http://www.kramerleather.com/products.cfm?categoryID=21
I don't think you should give up on shoulder holsters, my understanding is that many women have problems with ones designed for men, find one designed for women and you may have success
Try a horizontal shoulder rig.
I know paxton quigly used to sell a 'superbra' that had a holster in it,but I don't see that on her sight now, some googlefu would probably turn it up
here is something similar
http://www.c-rusty.com/pages/holsters/Ladies.html