Hi Hulagirl,
I got the Large BB cups only (I got the machine second hand) from www.gismostore.com, the guy's name is Mark Barker, he's very helpful and they're quite cheap. Are you using BB cups or NB cups? I use the BB cups because they are deeper with a smaller diameter so they fit on my chest better and then take longer to fill. I'm not sure what I'll do if I grow out of the BB large as I have the NB large which are the same diameter as the BB XL but the depth of the BB medium and I can't get a seal, even one at a time using the BB machine to suck hard. I've ordered my own latex to see if as well as making a cover for the BB domes I can make a chest mask to make the NB cups fit. Also from the BB I've developed a small area when the skin is slightly torn near the armpit, this felt a lot better with the rubber sheeting Lucy is trying so I may use some of that.
Here's the dimensions of both types of cups so you can see which will fit you:
NB Cups:
Small: Base diameter = 9cm Height = 9cm
Medium: Base diameter = 11.5cm Height = 11.5cm
Large: Base diameter = 13.5cm Height = 12.5cm
BB Cups:
M - 105mm diameter and 125mm depth
L - 120mm diameter 130mm depth
XL - 135mm diameter and 150mm depth