There are always more potions... although early in Act I you might be better off waiting. By the time I finished Act I I was rolling in both potions and cash (and I don't do any of those stupid arrow tricks, or whatever), so don't worry about those.
As for the empty dungeon, it happens sometimes. In my Act II BF, I didn't have a single boss in dungeon one, I had two in dungeon two, so I presume that I've got three left in dungeon three. It happens. The perils of random generation...