You can have a total of 3 trees. If you haven't planted them all yet then your villagers have more planting to do. Also make sure you always have a child in your tribe so that they can gather mushrooms when food is low.

Until you have a secure food source I wouldn't let your game run overnight by itself and don't have a population larger than you can feed.

Also, when there is no food too pick, I suggest putting everyone on Researching to stock up on tech points. You want to purchase more technology so that .