Gday Nick,
Thank you for sharing your experiences so honestly with us.
A strategy that many punters use is exit if the close is above the upper Bol Band and RSI (14 day)is > or near 70% ....not the Holy Grail of course (there isn’t one) but it would have given you pause to think twice about entering CBA on such a high. Of course many times a stock will just catch its breath at such a high and continue soon after. Never mind if you miss it ... there will be plenty of other opportunities every day to get in at the start of a trend.
Another warning sign is if Big White candlesticks and range/ATR get well above *2...tighten your Stop Loss if you are already on board.
I admire your coding skill, but no point in reinventing the wheel. For a few hundred dollars purchase Tradesim (or trial it very cheaply), which works perfectly with Bullcharts and other software to backtest any theory you like. If you are able to write the indicator in BC or use one of the many preset ones, it’s a cinch to backtest it in seconds over many years and hundreds of stocks using Tradesim.
If you do backtest a system be careful of past post betting...using “if it CLOSES above x...” and assume you would obviously have been on board that stock earlier in the day. You don’t know where the close will be. The Big White Candlestick of the morning could end up being a Shooting star or worse in the afternoon. You’d have to realistically test a system by writing ..enter at High,Close today, or Open next day.
I incorporate any successful indicators into Excel to automate my live scanning, then most important of all eyeball the weekly, daily, and one minute charts of the codes it throws up.
Good luck, mate.