What is a good bb/100 for 2/4 NL 400 6 max

[RikaKazak]

Hi,
I'm new to 2+2, right now I play the NL 400's 6 max, and my confidence is getting blown away. Just had a -$3,000 day (2 set over sets, and one all in on flop overpair (me) vs. tptk)so I don't feel I play horrible, just don't know really how good I am. Meaning am I average winning player, below average, just a grinder???? Just curious where I'm at and wondering if others could tell me how they're doing to see how far I am behind a solid winning playing on NL 400 6 max. My winrate is 4.5 PTBB/100 and that's after 46K hands. What is a good winrate that I should aim for before I move to 600/1000???