Hi Helen,
I have to say that it would concern me that the losing trade you had (-18) was equal to or larger than 3 of the 4 winning trades. I would argue that it is prudent to aim for twice the amount of points per winning trade than per losing trade. Now I know that you may say that the winning trades did not offer the opportunity to get more points which is fine. I would, however, say that the losing trade of -18 should have been closed much much earlier. The reason for this is that your average winning trade gave +15.5 points but your average losing trade gave -18. To be successful with this would require being right more often than being wrong. You may well have a method that allows that but if you dont and your trades average out at 50% win and 50% lose the long term effect will be net losing.
Of course using a SB company means that you have bid - ask spreads which would not be the case with your IB account so the situation may be somewhat better. I hope you dont take this as negative as it is not meant to be, like others on the board I just give my views and of course they are just that.
Good Luck
Paul