I think the problem is your confidence. particularly when your plan frequently gets ruined by market whipsaws, you(subconcious)will try to find saftey/certatinity, avoid those very profitable trades and chase those "looks safe, sounds great" trades, but actually they are very bad trades. I have this problem too, after I read several psychological books, I realize it and I corrected it.
a trading plan is important, but that does not mean you can can do anything since you have a plan. you need patience/discipline to select the very trade which can follow your plan, this will boost your confidence. if most can work out under your plan, that means you are disciplined and you know how to find a trade which fits your plan. if you want to use $0.3 stop loss to trade a 100+ stock, and want to gain 3 or 10 points, then most likely it is a bad plan, I traded MA using $0.3 stop loss, but I find it is not suitable, lost of time I am right in the general direction, but I lost in those minor whipsaws!
trading is an art! when to put stop (not like some one said, you should always have a stop). which amount is right, when to hold, when to liqidate, when to enter, and forget about risk/reward ratio (market does not work that way) .... I enjoy it very much. after three years in the day trading business, I find I accumulated 300k+ annually from my tiny 30k account!