The existing guidelines of 1GB RAM for “small” Discourse and 2GB ram for “medium” Discourse are quite reasonable and valid.
Swap is always recommended for Discourse. You can check free -m to determine how much swap is in use. In typical use you should see low swap use, like so:
total used free shared buff/cache available
Mem: 2001 1343 107 218 550 253
Swap: 1023 175 848
If you see high swap use – if used was 900 instead of 175 that indicates a problem, that the instance may need more physical RAM.