What does your Activity Monitor show? You can sort the list of processes in the memory tab, so the memory use shows the processes that use the most memory. Which processes appear near the top of that list?
What does the Memory Pressure graphic show? Still green? or yellow, or even red?
And, you might find that CPU usage is also relevant, and not memory use alone.
But, what affect does even low memory have for you? Do you notice slow response, significantly more now than before your upgraded to Catalina?