Further on poolSize and connection count in a sharded cluster

Trying to get a handle on expected poolSize and we’ve looked through the other posts here. Latest nodejs driver/nodejs v14; 3 shard cluster (4.4.9) with 3 voting/2 non-voting members in each plus 3 member config replicaset. 7 mongos, each with a number of nodejs applications accessing the cluster (all with connection pooling in the applications).
Is our maths right:
For each application connection to mongos, there are 6 monitoring connections to other mongos, 18 monitoring connections to each mongod (3 x 5 + 3), and then the default maxPoolSize (5) times 18, so per application we could expect 114 connections?
We are seeing a lot of connection pool constraints messages in the mongos logs and we’re just trying to adjust things so it quietens down the reconnections.
Any guidance or clarity very much appreciated,