This is a very good game.
At first I didn't realise it was your first game, that makes it even more amazing.
It reminds me a lot of touhou, the bullet patterns are great. Sadly I didn't see all of them, the sword boss is really hard to me. Maybe I just need some more practice.
The music is also great and fits well.
Overall the game is very good but some things can be improved. A first thing to improve is the hud. As it is now it looks really boring, just some text and numbers floating in space. Use some icons instead of text, for example a heart instead of 'lives'. The enemies seemed a bit weird at first, it feels more like I'm fighting abstract shapes in space. The bosses have a rectangle around them, I think it would look a lot better if you lose the rectangle (visually). The sound changing when a boss is almost dead is a great touch, and using the rectangle to know how much health the boss have seems unnecessary and looks a bit unprofessional.
Overall the graphics can be improved, but the gameplay and music are great. However, a practicemode with unlimited lives (or just a lot of lives) would be great, maybe consider adding one, and make it so the highscores for practice don't get saved.