Hi Oscar,
I couldn't listen to your composition but as you are interested in composition I highly recommend you to get this book:
William Russo – Composing music – A new approach (University of Chicago Press)
The best “teach yourself” to compose book I ever come across. Explores all compositional techniques by means of progressive and carefully thought out exercises. Even if you do not plan to compose, going through all the exercises in the book will help you to understand what composers are trying to do, and will lead to a much solid appreciation of the pieces you are learning, well beyond the simplistic emotional response “I like/I don’t like”. Highly recommended./Bernhard