I have the Kangzhu pump. Though, I think the mistake I've been making is that I'm pumping too hard. I have bruises left behind on the top of my chest. Could pumping too hard prevent breast growth? I have swelling that lasts temporarily.
I don't think it will prevent growth.... growth is more about the hours of exposure.... How long are you pumping per day?
I'm not an expert, but I don't think so.
I get red marks anyhow- no matter how hard I pump. There is no need to worry if they go away within a few hours.
How much of your breasts are touching the domes? I really think that even though the vacume is pulling your breasts into the domes.... if too much of the breasts is touching the dome then they are being compressed... not expanded... I figured the out on a set of home made domes when I blew the apart while wearing them...