Maybe try breaking some crates in skull caverns and see if you can find some luck rings, assuming you don't have them already? Other than that, you just have to grind it out, sorry. If it helps, you've been very unlucky?
Some math:
The chances of finding a treasure floor are 1% + daily luck/10 + luck buff * 1%, where the daily luck ranges from -0.1 to +0.1, that is, -10% to +10%, and the special charm from the rabbit's foot adds 0.025 to daily luck. So in your case, the chance of a floor being a treasure room is 1% +12.5%/10 + 5*1% = 7.25%, or 7% if you don't have the special charm yet. (Plus 1% for each luck ring you have on.)
It's worth noting that seeing the 120th floor doesn't mean you've actually had 120 chances at treasure floors, because you skipped some of those floors via drop shafts. IIRC it works out that the number of floors you've actually seen is on average half the final floor number, so on average you probably had 60 chances at treasure chests.
So the chance of not seeing any chests is (1-0.0725)^60 = 0.01, or 1%.