About the player bullets looking too similar to the enemy ones. Yeah I know, I knew when developing still. I planned to make them be sprites while keeping the enemy bullets as circles but I ran out of time for drawing stuff and figured it was more important to have a complete level instead. (everything level design was made on the very last day, most of my time was spent programming systems, which is what I enjoy the most)
As for the bullets having different colors having no different behavior, I really don't see the issue with it. The only real difference between them the trajectory and size really, all you have to do is dodge. Having bullets with meaningful distinct types is 100% something that can be done but it's not what I'm going for with this.
So If all the bullets are the same type, then they all should be the same color? It's more of a matter of opinion and I know a lot of games like this do it but I personally don't like it. A) The individual bullets all look at least similar and are easier for them to blend together, making the readability actually worse. B) You really need for it to be clear what is and isn't a bullet you have to dodge, so long they all have colors that contrast well with the background it's fine. C) I just think that it's prettier this way.
I didn't think I was going to write this much, thanks for the feedback either way. It does sound like you liked the game despite your issues with it so :)