I like that one alot, the only thing i can find a bit off in my eyes is the size of the saucer section, you say youver based the nacells off of the shape of the ship if it were split in half, but the curvature of the nacells is steeper than the saucer, perhaps widen the saucer a little bit to achieve some extra symmetry?
but overall, a very well drawn and details design concept. Kudos!