Hi S4mmi,
It does feel a bit scary when the skin around the domes really tightens up!

To be honest this is the only thing that stops me from pumping any harder as I tend to feel the discomfort outside the domes first rather than on the breasts themselves.I currently use the smaller domes as these are recommended for a size A-B ( im an average A cup at the mo-but gradually getting bigger YAY!!

) & it's when I use these that the stretching feeling between the cups happens the most.
When I tried the medium cups they seemed to concentrate the pressure & suction on the breast a lot more than the surrounding skin as the base of these is a bit wider, so comfort wise i'd rather use the bigger cups but they are not really intended for my A size according to the instructions- I don't know what would be best as I don't quite fill the small cups yet

Any suggestions welcome!!
As for pumping time, I use the NB for about 1/2 to 3/4 hours every single night & gradually increase the pressure every few minutes, this has worked very well & I began to notice a change in the fullness fairly quickly! Sticking with regular use & building up pressure & wear times seems to be the key to success with this!

Love to all, Sarah x