It sounds pretty damn amazing thus far, but I'd love to see you try and incorporate a good few woodwind instruments as sort of counter-melody/supporting lines; they generally work very well with strings in this regard.
I'm also noticing that there I'm hearing little to no brass sound in it, and that's something I'm not used to with you quite frankly. Might I suggest using a French Horn or Baritone/Euphonium to kind of fill that gap if you haven't already incorporated in a later part?