World's bubble fruits

This game is so addictive! However, I’m not understanding how the score is determined. I have passed levels up to 160, it looks as if that is the last one. My problem is, I can’t get 3 stars on level @60, no matter how hard I try. I have had 16 left over shots and moved very quickly, but still can’t get the three stars. My score has been just short of 30,000 still only 2 stars. There is no way to contact support and you have to find the name of the app, it appears to be somewhat of a secret. I went looking for it in my settings where all of my other apps are, but it was not listed anywhere. I have had as little as 4 or 5 left over and had a higher score than when I had 12 left over or even more. I’ve gone as fast as I could, made difficult shots, still, there is no consistency of the scoring that I can see. I have been trying daily for 2 months and cannot get that danger third star!