Well this work bears the traits of exploration and discovery. I can hear you exploring
with this piece. The basic
harmonic language is Common Practice Period (meaning the pervasive use of tertian harmony (chords of stacked 3rds) and functional tonality), but you don't yet seem to understand the principle of Closely Related Keys (simply put they differ by only one degree (added or subtracted) in the key signature, whether major or minor mode*) and how to move from one to another (modulation). From about the 20-40 second mark, you use chromatic tones that are out of context. As a composer you must a have a reason
note you write, understanding it's purpose and context. Your texture is basic, and known as treble-dominant or homophonic in that there is a high melody part supported by harmonic activity below: a lot of great music has been written this way. There seemed to be some shift(s) of meter (not tempo) that were not immediately inteligible. The most difficult thing you will likley need to tackle is to understand harmony, funtional tonality, how to use non-chord tones (dissonance), and form (the larger shape of musical works). This is no easy task and is in fact the
reason many go to college/university/conservatory to be instructed in. Music is a language, and as such it has its grammar, cadences, syntax, lexicon, and literary forms, not to mention styles. It is no minor task to prepare oneself to be sufficiently skilled to compose. If you have patience and tremendous
dedication, to the point of great sacrifice, then this is something you will be able to develop. You are not too old, but most your age pursuing composition would already know all the basic science of this art. As with any other artist, you learn the craft and the history of those before you. Then you may be able to contribute something new and interesting. Good luck and study very hard!
* e.g.: F major/ D minor - C major/A minor - G major/E minor. (6 closely related keys)