Sorry for being slow to load your game,
Your three biggest problems are using the default city manager, not enough science focus, and an inconsistent game.
You can get away with the default manager on lower levels, but you will never have a good game on any level unless you manage your citizens. It can be a hassle, and will be a barrier to high level play if you want to move up. I don't want to go deeply into it, I would suggest jumping over to the Lets Play section and watch the first video from one of the Deity players such as Light Cleric, Moriarte, or Maddjinn. They will explain why they are managing their citizens in the way they do.
Your capitol is more than big enough to work a lot of specialists, but you are only working 3, and none of them are science. You are working some science in other cities, but you are also working merchant and engineer slots. You do not need the gold or hammers, an you will generate GE's and GM's instead of GS's. Remember, all victories are based on tech, you can't neglect science.
You bypassed plastics and are teching to radar in the save, and you still do not have a school in the capitol. Just rush buying a school in the cap, and then working the science slots in all your cities will boost your bpt by ~120. Had you gone right to plastics, you would probably be well over 1000bpt right now, already done with radar, and possibly done with rocketry because of it. Teching toward military techs and not having the bpt to get to them fast is a game killer. Once you hit modern era, getting plastics is a top priority, the only thing you might detour for is biology, and you want biology for hospitals. If you do not want hospitals, then the path is plastics -> bio -> radar -> rocketry.
The inconsistency is apparent with your military and your tech path. You are teching toward radar, but you only have 4 aircraft. If bombers are the goal, then you want a dozen or so GWB's ready to upgrade. Try to always ask yourself if what you are doing is consistent with the rest of your game. You have 8 artillery stacked up on Poland's border, but you are not at war (inconsistent), these artillery are threatening an expo rather than the capitol (inconsistent), you only have 2 melee units with the arty (inconsistent, you need 1 or 2 more meat shields). I am sure you get the idea. I would add that 8 arty is too many, 6 is plenty enough to sweep to the east if you have 3ish cavalry for city capture.
There is also inconsistency with your policy choices. Autocracy is for war, but you are not at war. Opening aesthetics and exploration is for culture victory, but your tech path is totally wrong for CV. For both domination and science, commerce to cheap purchasing is almost always the best.
Some other issues,
3 workers is waaay to few for an empire that big.
Sippar. I don't get this city at all. It sucks, its location sucks, no idea how this city came to be.
Borsippa also sucks. it has no redeeming qualities.
Nippur should have been settled south on the hill across the river
Dur-Kurigalzu should have settled west on the hill
Never settle a flat when there is a hill.
I get no barbs, but it really hurts you more than the AI.
No spies hurts you a lot more than the AI, if nothing else, you can put spies in cities you are targeting to get line of sight for your artillery and bombers. With no spies, you will have to send a unit into to look at the city.
no GS's. I am assuming you either got none because of the default city manager popping GE's and GM's or you bulbed them on earlier techs. Even in late game domination, they should be saved for after plastics.
Hopefully someone else will load the game and give some feedback as well
Happy x-mas