Breakeven is just another period of your development, then next stage will be slowly making consistent smaller profits. As far as increasing size, I wouldn't, I would find ways to get in a little better which in turn reduces risk and also increases profit. Once your ave per trade start increasing, after six months or so of increasing monthly profits, then you can start increasing size.
As far as other issues OP have discussed, fear, trading plan, greed, or even intuition, don't fall backwards. A friend of mine is the best plus 2 tic trader I have ever known, he been at this amount for a year, he has a gift of knowing when to get out faster than I will ever know, but fear of taking the trade where the brain says "NO" is stopping him from acheiving a great deal more.
Backtesting is where it is at, if you can't backtest 100 shares profitably and somehow increase ave profits, more shares is not the answer.
Good luck.