Well to be honest with you, although I found it challenging I did not find it that hard. But than again, since I build the game I know where some hidden ammopacks lie and which weapon to use at the right moment. You should use your melee weapon as much as possible to save ammo (read against as many melee attackers as possible). This way you should have enough ammo against ranged enemies. Futhermore, you can avoid some enemies to if your ammo is depleted.
But this is definetely a mistake of mine, I did not think of the fact that this was not as clear and obvious to others than to myself. However, I have taken this into account for the next version so I advise you to wait for that one.

And you were still not in map 2 :P, you were in the second part of map 1 }:). In the next version the second part of map 1 will not be so annoying too btw. Anyway, the reason why I asked that because in map 2 you get the third weapon (it is behind a destroyable wall) so you have alot more ammo to waste on foes.

May I ask where you stick to walls/ground? This is probably a bug.