I think that's why in calculating our money management, we have to consider how much capital we have.
It's the basis elements in deciding the lot sizes for each trade. I personally believe it's normal to expect more from small capitals. What I mean is, try to look at it in different aspect. Say, you have only $50usd to be used in forex investment. From that $50usd, I'll take $10 and open another account for it.
For the account of $40usd, I'll trade using a safer money management - say, with risk less than 10% per trade. However for $10usd account, I'll use higher money management risk about 20% to 30% per trade. That's what I mean by expecting more from your small capitals, but do it in a wise way.