As some of the comments have said, the game is really difficult. I tried for some time, but never even got to phase 2 (don't even know what phase 2 looks like). And I never used dash at all because of how limiting it felt.
Something that might help is making the hitboxes a bit more forgiving, to make the game feel more "fair" for the player. For example, I noticed that the propellers on the circle enemies actually kill you when touched. It also sucks a bit when a bullet just grazes the black outline on the slime then it kills you, not exactly what you'd expect. Or otherwise you can be a bit clearer on the hitboxes, one way is color-coding them, or even to have a hotkey you can hold to see the exact hitbox on the slime.
That's just my opinion though. Overall it was a great game, love the aesthetic and music.