I have C3C; I could not open your save with the vanilla.exe but I could open it in Conquests.
Yes, you have a building fixation. That can be cured.
However, you have only defensive units. No Archers or Longbow, just Spears and Pikes. You do not have a source of Horses, so even though you know Chivalry you cannot build Knights.
Trading
You need Engineering so that you can cross rivers freely. If you talk to the Aztecs and offer them Theology, they will give up Engineering, their World Map and all 48 gold. No one knows Invention, so you cannot buy it right now. Sell Education to France for their WM and all their gold. This will kill The Great Library, located in Paris. No more free techs for Joan.
Luxuries
You have only two, which means your markets are under-employed. You need to get roads and harbors to connect you to other civs so that you can trade for more luxuires. Getting new luxuries is better, since once they are yours they tend to stay yours. Trading just gets you that luxury for 20 turns, unless the AI declares war on you.
Techs
I would switch from learning Democrary to Invention, due in 7 turns if you traded like I did. Then learn up to Military Tradition (for Cavalry, a 3 move unit) before getting Astronomy and the rest. Ignore the optional techs, except MilTrad. You should be able to pick up the optionals in trading and maybe some of the required, too.
Workers
You have 27 workers, which is good. But have them work in gangs, not alone. One worker can road a tile in 3 turns or 3 workers can do it in 1 turn. Which is better? I prefer 3 worker roading one tile in one turn. That gives me two extra turns to use that improvement, which means faster movement and more commerce for a new road.
City Improvements
Library is generally better than Temple. The upkeep is the same, 1 gold per turn, and Libraries help you learn things faster. Temples add culture (so do Libraries) but not much else.
In your good production citeis you don't need a Courthouse. Courthouses reduce corruption, but if the city has little to no corruption it is not needed. My rule of thumb is to ignore a Courthouse unless the city is producing 6 or more shields per turn and 3 or 4 of them are corrupt, leaving on 2 shields per turn (net). If a city is producing 6 sheilds and 5 are corrupt, a Courthouse is a waste of effort. That city will stay corrupt. In those cities build workers, settlers, artillery units or wealth.
Cathedrals and colosseums are generally a waste, unless you are trying for a Culture Victory.
Military
Build more offensive units. The AI respects a strong offense more than a strong defense. You are in Republic, so don't need MPs in your cities. You may need garrison units on the borders, but not generally in the interior of your empire.
Build some rock-throwers too. They can help you prevent losing units when they attack first.
City Placement
It looks like your core cities are all 5 tiles away from the capital. While vanilla does have some quirky aspects (City Rings, for instance) consider building only three tiles from your capital. That makes your cities within walking distance of each other, which in turn makes it easy to shuffle units around.
Build more cities.
Overall
I think you have a good game going; wish I had time to finish it.
La carga es la que hace andar al burro (it's the load what makes the donkey move). In your case, the best cure for building fixation is playing on a higher difficulty. When you begin to see more pressure from the AI, you'll know it's time to build military. Then you'll see that you can't build units and buildings at the same time, and will be forced to chose. Afer a couple losses, you'll start to change your strategy and voila! Your fixation is cured. 
