There's really no good answer. We hit a time where we have to be a little patient. Continuing to scout provinces and either cater or fight them will get you extra expansions to put down so you have more room for buildings, but if you scout too far, it will get so hard that it becomes difficult to progress. At some point you have to settle for incremental progress, and start digging into the most efficient use of each square. Maybe you can use one less factory becuase the bigger factories are little more efficient, maybe you just have to wait a while until you can put down another square of land