Interesting piece. You're right it is sparse but I think it works for the most part. The vocal is great. I like the contrast of the distorted synth with the sweetness of the vocal at .43. I think at around 2.40 instead of going back to the bare bones again there's an opportunity to build up a little towards the end with another growly patch. Can never have too much distortion! Nice job on this, it's a cool tune
When she sings 'leave me alone', the word 'alone' disappears. Can you fix that?
You're right about the sparseness, but don't add too much, kay? And when you get the extra layer done (strings?) consider ways to mute it at certain parts and let that sparseness through again. It's a great tune. And she can really really sing.