Hi Sunny, thanks so much for leaving a comment and your feedback. I'm glad you enjoy playing the game.
The movement speed - yeah I played around with the different ship speeds. The first few builds of the game had everything moving a lot faster, here's an imgur link of a very early build https://imgur.com/a/QK36CXg I eventually slowed it down to match the music and I also thought it added a bit of tension. Also the slow movement speed makes the boost from the shield ability more noticeable. I think the game could be sped up slightly though.
The enemies spawning - I kept running into this problem too and decided to implement the "egg" looking pre-spawned enemies so you could see where they will appear before you will actually be killed be colliding with one. The problem then is that if there was too much headsup on where the enemies would spawn it broke the flow of the gameplay and you would be able to easily shoot at where the enemies would appear. I tried to find a balance on this and made the "egg" pre-spawn animation appear briefly, but I admit I'll even collide with the spawned enemies leading to a frustrating run. I think the headsup on the spawn time could be slightly increased as well.