I recently started designing T-shirt’s. I want to sell them and my hubbys job has a bazaar at work…

I recently started designing T-shirt’s. I want to sell them and my hubbys job has a bazaar at work where employees sell homemade crafts/items once or twice a month. It’s a pretty big company with a lot of employees our age so I feel my shirts could sell. But I’m unsure of how many shirts and of what sizes I should make ahead of time. Any suggestions? I have 11 designs so far that I would like to make. I’m just worried about making too many or too few.