Your bankroll is simply defined as the amount of money which if you lost, would prevent you from continuing to play poker.
If you can not deposit more, it is obviously the amount in your account.
If you can deposit, it is your account plus the amount you are willing/able to deposit to continue playing.

If you can't beat the game, bankroll management rules do not apply.
They are to prevent a winning player from going broke.
If you are not a winning player you should play the lowest limits possible or quit playing altogether.