Android : Web view content gets displayed differently on smaller Android Device

i am facing a pretty weird issue here.

I am programming an android app, in wich the user is required to login or register. On clicking the register-button, my login - activity creates a new instance of my web view fragment, in which the web view its shown. It also sets a "back to login" - button visible. All that stuff worked perfectly fine until i tested it on another device:

So what you see on the right phone is the web view filling out the whole screen, displaying all its content (button and label are all web content, just the blue button at the bottom is native). On the left phone the web view also fills out the whole screen, but the content seems to be no bigger than a centimeter. I tried defining other attributes for the web view like "fill_parent" and "wrap_content" but it doesn't chance anything, exempt that with wrap content, the web view on the left screen scales down to the size of less than a centimeter.. Did anyone experience these issues as well? Any ideas are much appreciated because i am really stuck here...