Hi Groovy ! Glad to see you still working on it !
I think you should set the gravity to 0, that's a very weird thing when we are in space to see our ball driven by gravity., and the main grief i have against your ball is the bounce angles on the shield that are completely "ununderstandable" (i hope this is the right word).
A thing that could help a lot (just my opinion), and i didn't manage to put the right words on it last time : your action is vertical, and horizontal movements are what make the game boring at moments (when the ship is too far from the ball, when the ball is catched by gravity, when the enemies are out of reach ...). So here is my thought: go the vertical path ! Literally ! You could stretch the screen vertically, like mobile screens, and increase the speed of the ball speed a lot. That would restrain the horizontal movement annoyance and give depth to your action. Furthermore you could put lots more of stuff in this new vertical space, and more action is what i need playing your game.
Hope this helps.
See ya !