I would start with two and then choose the best one to fill the entire space. It appears as if you only have less than one square meter (0.784 m3) for your entire grow space including ventilation, lighting, filtration, etc. Even one small indica dominate autoflower can easily fill your space if given the proper environment. Putting too many plants in a crowded space could cause airflow problems, mold problems, etc. The plants should not be touching each other for proper healthy growth.