Wow Temp! You've made a lot of progress. I love the boss artwork/sprite!

One big suggestion: use the left analog stick for controlling the ship as well. The D-pad is inaccurate and many people hate using it.
A little suggestion: Have a "kill screen" powerup. Something where when you get it, you hit another button or L1 and it will kill everything on the screen. Those came in handy when I played these sorts of games back in the day.

All in all it looks like a great start for your first foray into developing. Keep it up man!