The cities need to buy and sell more goods not meaning that there should be more types of commodies but the commidies between them need to be more.

Example.
A player who has limited time can use log in and run to a planet and mine a wile, log out come back later mine some more, repete doing this untill they have a cargo full of material.
Then he will try and sell this, if the player can manage to sell the goods he will get a sense of accomplishment and will probably want to do this more giving.

As is to sell a cargo load of anything takes hours of city/planet/system jumping because the cities buy so little quantities of the ores.

Sounds good. Maybe what I will do is make it relate to the value of the cargo. If it is a cheaper cargo, they will naturally want to trade/have more. This gives a greater advantage to cargo-based ships on trading, too, since they can haul as much as they can fit early on, it's not limited by finding the right trading ports. Thanks for the suggestion!

also it would be usefull to be able to tell how much cargo space you have and how much you have left wile in space.
I like to save one or 2 cargo slots to pick up what ever I have to kill on the way home.
Sometimes I wind up having to dump minerals to carry the loot.