The trade opened at the wrong size

Size problems come from three places, and the first one is by far the most common.

1. Risk is set in two places at once

Both the indicator and the EA can carry a risk or lot setting. If you fill in both, they compound and you get a position larger than either number implies. Set size in one place and leave the other on its default. Decide which one, write it down, and never set the other.

2. The broker's lot step rounds you

Brokers define a minimum lot and a step. A calculated size that falls between steps is rounded, and on a small account that rounding can be a large proportional change. Check the symbol specification for minimum volume and volume step.

3. Gold contract size is not universal

One lot of gold is not the same quantity at every broker, and neither is the value of a one-point move. A size that was correct at one broker can be materially different at another with the identical number typed in. Always re-verify size after changing broker, and always test with the smallest permitted volume first.

How to verify without risking anything

Set the size to the broker's minimum, take one live trade, and compare the resulting position against what you expected. One small trade answers the question definitively and costs almost nothing. Use the position size calculator to work out what the figure should have been.