Hello !
Thanks for putting your game out there, it's really impressive that you made such a "complete" (that is, every aspect covered, programming, design, graphics and music !) product at such a young age !
If I can give a few words of advice, it appears to me that, now you've proven you're capable of getting an operational game out, the thing that would really get your production to the next level would be to find ways to make it unique and interesting in your own, personal take.
For instance, when Gradius came out, it was super interesting and fresh and new, because it was this cool game concept people weren't used to ! But that made it more difficult for other developers that, later, wanted to make sh'mups, because they had to develop their game keeping in mind : "Why would people play my game, and not Gradius instead ?"
And if we think about it, that's why Touhou worked : it's basically "more intense Gradius", but with a completely revamped visual universe and signature music to go along with it.
The best indie games can sometimes be traced to the same idea, but with freshness and creativity coming from every aspect : What makes Super Meat Boy different from Mario games ? Not only is the gameplay a lot more intense and challenging, the visual universe is also completely different and fun, it has really kick-ass music, and it has some unique game mechanics to it. (And then, of course, you can also have indie games that kinda do their own thing like Crypt of the Necrodancer, or Antichamber !)
My point is, while it's generally a bad idea to be original JUST to be original (then, your game becomes a gimmick...), I think it's always healthy and important to challenge your game's design and ask yourself : Why would someone pick this game instead of X popular, similar game ?
I feel like that's the one thing you'd need to work on to move forward with your development - though I have no doubt great things will come from you in the following months and years :D
