first of all I'm sorry, that my response took a while but I was quite busy at uni and had very little time to play around.
Still I played around the game and came up with a possible solution. Perhaps you could ad a pin so that there is something which just points at the spot where the bubble is going to end up.
But to be honest I couldn't think of a way to get that working without haven trouble with the edges of the screen.
All in all I just kept playing and got better (I still didn't get more then 590 points
) and actually think of it as playable right now.
It needs a bit of time to get used to it but in the end it's fine.