MongoDB Sharding - why my data isn't being distributed on all shards? - mongodb

Question

I created a MongoDB Cluster with 3 shards, each shards contain 3 mongod-processes. My Cluster also contains 3 mongos and 3 config servers
In the connection string I put the 3 mongos
mongodb://user:pass#mongos1:27017,mongos2:27017,mongos3:27017/mydatabase
In the picture you can see that dbShard_2 has 1.19GB of data while the others are almost empty with only 4KB. But on the charts you can see that there is also read/write operation on all shards. Is everything fine or did I have made some wrong configurations? shall I worry?
I left the Cloud Manager do the whole configuration for me, I didn't set these by myself manually.
Here you can check my sharding status
mongos> db.printShardingStatus();
--- Sharding Status ---
sharding version: {
"_id" : 1,
"minCompatibleVersion" : 5,
"currentVersion" : 6,
"clusterId" : ObjectId("XXXXX")
}
shards:
{ "_id" : "dbShard_0", "host" : "dbShard_0/dbnode-0.x-app.com:27000,dbnode-1.x-app.com:27000,dbnode-2.x-app.com:27000" }
{ "_id" : "dbShard_1", "host" : "dbShard_1/dbnode-0.x-app.com:27001,dbnode-2.x-app.com:27001,dbnode-2.x-app.com:27002" }
{ "_id" : "dbShard_2", "host" : "dbShard_2/dbnode-0.x-app.com:27002,dbnode-1.x-app.com:27001,dbnode-2.x-app.com:27003" }
balancer:
Currently enabled: yes
Currently running: no
Failed balancer rounds in last 5 attempts: 0
Migration Results for the last 24 hours:
No recent migrations
databases:
{ "_id" : "admin", "partitioned" : false, "primary" : "config" }
{ "_id" : "mydatabase-staging", "partitioned" : false, "primary" : "dbShard_2" }
{ "_id" : "mydatabase", "partitioned" : false, "primary" : "dbShard_2" }
{ "_id" : "test", "partitioned" : false, "primary" : "dbShard_0" }
Cluster