Ammo, stamina and health

Im only three hours in. There seems to be a real lack of ammo in this game and bullets do very little damage to zombies etc

If there are more than 5 enemies I'm guaranteed to be dead, because I also have no stamina either to run away (and it takes 20 working days to get on my bike it I do make it there).

Will the availability of ammo increase? Does the damage done increase? I'm searching everywhere and finding sweet fuck all, 2 bullets here, 4 bullets there. Then it will take 5 bullets to kill one zombie. Yet I'm surrounded by like 20 at a time.

How can I destroy nests and progress with no ammo or decent weapons.

I'm trying to get into this game and like playing but it's getting a bit jarring and I don't want to uninstall.

Is the game a slow burner ?

Any tips much appreciated.