Hmm... Yes, it seems like 10 GBs will not be enough for live 200 VMs and 6 hosts (btw, good ratio for VMs per host!). The reason for this is that we keep 20 seconds for the last hour for every metric and for every object. In addition to this 5 minutes data samples are stored for the past 14 days for granular past performance reporting.
Given all that, I would suggest either to switch to a full version of SQL Server, select advanced scalability mode or you can ask our support to assist you with disabling some performance counters you don't plan to monitor. Hope this helps!