Fair warning here: I’m a hardcore, hardwired SF fhan and a role playing gamer of the gearhead variety, so my advice may be harder in tech terms than you want.
I try to make shipe, thos quite different from yours. I prefer the star wars/battlestar galactica genre of hard lookign ships with lots of angles and planes instead of smooth curves and such, I just never see the poijt of streamlining in space.
The things to think on when making a SF ship are basically what kind of tech and science is it based on, what is it supposed to do and how does it do it? Does it enter atmosphere? Is it space only? Does it have FTL ability, shields, weapons, etc?
Your ship’s a cargo vessel, so it needs cargo space and ways to quickly and efficiently load and offload cargo. What are those things on the sides? Are they some type of engine housing, force field generator or cargo bays? If they’re bays add cargo doors to them.
Does the ship land? If so hows doe it land? Does it have landing gear or does it land on water?
Is the hull streamlined for atmosphere entry? Does it use aerodynamic fields to atmospheric work?
The more detail you put into the technical thought the better the ship turns out, IME. On ships I try to make (I’m still weak at blender) every part has a function I can describe.