The trading system based on the XWAMI indicator signals with an ability to change the volume of a forthcoming trade depending on the results of the previous trades for this trading system. Trading signals are formed when a bar closes if a trend has changed (which is displayed by cloud changing its color).

The block of input EA variables is added for managing volumes of opened positions:

input uint    BuyTotalMMTriger=5; // Number of the last Buy trades for stop losses count input uint    BuyLossMMTriger=3;  // Number of loss-making Buy trades to decrease MM input uint    SellTotalMMTriger=5;// Number of the last Sell trades for stop losses count input uint    SellLossMMTriger=3; // Number of loss-making Sell trades to decrease MM input double  SmallMM_=0.01;      // Share of financial resources from the deposit used in a trade in case of losses input double  MM=0.1;             // Share of financial resources from the deposit used in a trade in case of normal trading input MarginMode MMMode=LOT;      // Lot size calculation method 

In case of such inputs and when selecting from the last five trades, three of which are loss-making in a single direction, the EA opens the next trade in the same direction having the volume of 0.01 lot. If there are less than three loss-making trades out of the last five ones, the position volume is 0.1.

For the generated EA to operate correctly, the compiled XWAMI.ex5 indicator file should be in the <terminal_data_directory>\MQL5\Indicators folder.

Default Expert Advisor's input parameters with stops have been used during tests shown below.

Fig. 1. Examples of trades on the chart

Testing results for 2017 at EURUSD H1:

Fig. 2. Testing results chart