That was a fun game. It took a few tries, but I managed to beat the boss. I like all the different bullet patterns, having them be so varied makes it fun to dodge them.
I wish getting hit didn't make you lose power, because it makes the gameplay last much longer than needed. The boss should also have a health bar, since you can't tell how close you are to beating him without seeing his health. I also think there should be sound effects when the enemy shoots, as well as visual indicator for your hurtbox as it's much smaller than your shop.
Overall, great job! I had fun playing your game.