With such a light mass you definitely need a high compliance MM/MI cartridge, try some decent vintage cartridges and i'm pretty sure you will be impressed. Look for the best possible stylus profile and a nice cantilever, normally top quality MM/MI from the 80's are very nice.
Or change your tonearm to something like FR-64s (very high mass) for low compliance cartridge.
Or change your tonearm to something like FR-64s (very high mass) for low compliance cartridge.