You have 23 stations.
Note: With those Mines you could have
more factories. Note that I changed race of some. Same features and looks, but cheaper. If you choose to expand and do have access to Boron SPP XL, then get one.
Even that is not using all capacity of those Mines.
However, your complex is formally
self-sufficient, with high margin. It does produce more energy than it needs to create crystals for the SPP and to produce those missiles. Once it has enough resources in stock, it will not need anything from outside.
I have created closed self-sufficient complexes. I did haul initial stock manually (usually crystals). I did give such complex 0 credits, and it never bought anything from anyone. I did have ships to haul off the end products. Therefore, the complex never sold anything either. Never saw a single credit.
Put other way: a self-sufficient complex cannot really "lose credits". Well, unless:
* If it has ships trading, those ships jump, and there is not enough surplus ECell production
* If ships have pilots that get their salary from the account of the complex
* If you allow too much intermediaries to be sold, which halts the energy cycle
I don't do "loops" any more, nor "closed systems". I now try to maximize trade with the NPC. That is where the credits come from.
Like Nanook said, a complex like yours can hold quite a lot of wares in stock and if your complex buys wares, then it converts credits into wares. Wares with a value.
If you do use Trade Mk2 buyers, there is probably nothing stopping them from filling the station stocks.
If you use CAG ... CAG by default fills resource stocks to 80%, but you can change that to a lower value. Similarly, you can control how much intermediaries the CAG will gather, and when it can "sell the surplus".