My opinion is no on another anemone. I know you've already been told that your tank isn't mature enough for an anemone, and it's obvious there's not much to be done about the one you already have. Getting another, IMO
, is a worse idea.
One of the mentors said something to this effect a couple weeks ago: you think your tank is stable. Your levels appear to be good. But throughout the day, as a young tank, the levels are fluctuating all day. That's one of the reasons an anemone is suggested for a mature tank.