[Xylocain]

It takes fewer hands than most people here think to get an idea of wheter you are a winning or losing player. (I think most people confuse it with determining actual win rate wich is basically impossible). What it comes down to is the confidence interval. Basically, you dont need a 95% confidence interval to make an informed estimation.

If you are running at -3BB/100 over 5K hands, your best assumption (~80%) should be that you are not a winning player (yet).

But stop worrying about your wirate, most people loose anyway. Sign up for session review and focus on improving your game instead. (or move down in limits)