Welcome to the forums, Nenad!
I'd say that at best, taking over the entire galaxy in this case is wishful thinking. With only 11 planets and only one home command station left, it will be an uphill battle in both taking planets and maintaining them, especially with three times as many waves as there would be normally since there are three players).
In this situation, I would probably just pack up and start a new game, if I wasn't reasonably near the goal of blowing the AI home command stations.
Good luck, and be sure to post screenshots!