I’ve just finished most of this model, still tweaking of course.
Any feed back well come 
I really like the overall look, but the final render seems too bulky, making it look more toy-like than life-like. Maybe that was what you were going for. If not, I think more detail, more of a sleek design would enhance the realism. Good job though in any case.
If its an atmospheric fighter perhaps - but a true space fighter would be unlikely to conform to a traditional sleek jet fighter type design. I think the Starfury or Gunstar are probably closer to what a practical, “real world” space fighter would look like.
interesting, i think more details are needed on it’s surfaces. the overall shape is a bit bulky but as moony said a real spacefighter does not need to be sleek, if those wide tubes jutting forwards from the fuselage are thrusters for reverse flight and turning then it is quite realistic. in the render it looks to smooth at the moment and needs some texture, also perhaps sharpen the edges if you want it to be atmosphere capable although the shuttle has a rather unstreamlined nose to avoid shockwaves hitting the wings during reentry.