Its going to stay a bit high with such small nodes... quite literally there is only 512MB jvm on each node.. that is they smallest you can possibly run.
Remember, the goal is about 10-20 Shards per 1 GB JVM : you have 1.5GB JVM so the goal would be about 30 Shards to you are still 2X. Again these are not hard rules, and with such a limited amount of JVM RAM it going to be tight.
And in general your indices are still extremely small, each indices / shard takes memory space in the JVM.
I would suggest scaling the cluster up to 2GB or 4 GB nodes. You can do that from the deployment screen just hit edit change the setting and apply, it will take a few minutes it will do a rolling change with no down time.
Me... Smallest I ever run is 4GB nodes, but that is just me, you can try 2 GB nodes first.
You can scale these cluster up to HUGE Terabytes of RAM and 100s of TBs of storages, which you clearly do not need at this point.
No reason to think about on-prem at this point.