Understood I am just relating best practices and why you are having issues.
Elasticsearch can run like this, BUT Elasticsearch will not run / will not run well if it can not claim the RAM it needs. So if 1gb of RAM works then fine. Also you can always start elasticsearch first let it claim its RAM then let the other processes "fight" of the remaining RAM.
So in this case you need to manually set the elasticsearch RAM as you just did... 1GB is pretty small... it may or may not work well depending on how many shards, ingest per sec, queries etc. you can always bump it up.
If it is not running well bump it up to 2 or 4 GB and start it first and so on.