You're experiencing the game's true balance here! The point of runics is that you should try to go as deep as possible without using them, so that you can use them on a powerful item that will make you reach the endgame. The point of this mechanic is that new players can burn their runics early on, so that they go a little bit further that they would do without runics. Experienced players, on the other hand, should try to keep the runics as deep as possible.
Regarding forges, there's a 1/8 chance to have a forge at a given level; except for the first level where there's always a forge. I believe it's the past it was 1/6.