Right, I'll try to address all the points in your post there. Firstly, I would not consider the percussion in the song, your melody. Mainly because a melody is (usually) pitched, and the percussion you're using is not of that sort. Also, the drum part is a strict rhythm part, not melodic, if you know what I mean. It's hard to explain. The "melodic-type stuff" as you put it should NOT be considered as "backup instrumentation", as you said. The percussion in the piece is pretty sub-standard - nothing special, so that is not the main focus of the piece. That is why the harmonic and melodic parts seem to be drowned out, when really they should be at the forefront of the song.
I'm sorry to hear about your accident. Though, drugs do sometimes improve a musician's work - this may be evident in this song you've done here.
As for the music theory, and other points I made that you didn't understand, I'd strongly suggest reading up on them. It is impossible for me to write every part of music theory and recording technology here, so I say try to find out about it yourself. Then, I will gladly answer any specific questions you may have. It's just at the moment, it's way too general.
About what I said in my previous post about your tonic chord being it being i (minor tonic [in maj = iv]) 7. Basically, the roman numerals refer to chord numbers in a key. Often (but not always) minor chords are written in lower-case (i ii iii iv, etc) and major chords in upper-case (I II III IV, etc). I was saying that your tonic chord (the root chord of the key you're using) is i (minor root chord in a minor key [chord vi in a major]) but with always with a minor seventh (interval) extension. I was suggesting that you should leave the tonic unaltered in places, as making the tonic chord a 7th constantly does not help aid the rules of functional harmony (if you're wanting your piece to follow that) when wanting to create a perfect cadence (V - i in minor [V- I in major]), as it does not give the harmony a sense of it being final, or 'finished' sounding.
I hope that's made some sense to you, and that it'll aid you a little with your music.