I went back and beat all the levels except the last one. I was able to beat level 10 after 5 or so tries after sleeping and coming back. Felt good. My iterations for levels 11, 12, and 13 were 5, 16, 30.
Also had a thought about what might be a cool level (if you haven't already done this): two enemy torpedo launchers next to each other, firing through a narrow channel you have to go through. Their shots are staggered so you have to weave back and forth to avoid them.