At first I kept getting filtered by the fat orange enemies, until I realized that you cannot damage their wings, after which I managed to get to the second boss a couple of times, but didn't manage to beat him. Tried different modes, but I don't think I noticed any difference.
I'd say that the movement speed is a tiny bit too slow for my liking, it' barely faster than slow movement. I also find it weird that the second fire mode slows you down. IMO, the enemies are also too big and take up too much screen space.
I also liked how you added the R key to restart, since I hate waiting for an animation to play out or something when you die, cause it feels like the game is humiliating you.
Can't say much else about it, cause despite making a shooter that has element of a bullet hell, I don't really play them that much, the only one I played a lot was Enter the Gungeon.