Don't try to fix what isn't broken.
People that say stuff like "your fcbet is too high" always seem a bit clueless to me, they once learned that there is a "perfect" number that you should have, and instead of analysing every situation and opponent individually they aim for certain stats. At higher stakes, these numbers become more relevant, because people are having a more exploitative approach to the game and don't just look at their hands like at 10 25nl etc.
Of course, certain frequencies could be exploited, but you always got to ask yourself if they are, and adjust accordingly, not aim for a number.
10bb/100 is really good, it's not likely to be sustainable, but that's fine.
Success ermee!
PS. Showdown winnings aren't
that relevant, this also depends on who you're playing. I doubt it has to do with the stakes you're playing and even some of the bigger winners got negative numbers there.