First of all, thank you for letting the player hold the fire button to fire, I am not a fan of button mashing in shoot 'em ups.
One thing I noticed is that the hitboxes are bigger than the sprites, so even when I saw I was dodging one of the enemies, I was hit with a ~5 pixel gap between the sprites. It's usually a good practice to keep hitboxes inside the visible sprites to prevent that. For concave sprites (like the X shaped enemies) I think that keeping the corners of the hitbox inside the sprite would be enough.
Aside from that, the controls and the gameplay feel pretty smooth. Good job!