How do you keep a small BTC perps loss from turning into a bigger one?

A losing BTC perps trade doesn’t mean the entry was careless. What seems harder is keeping the loss within the amount you were prepared to take once price starts moving against you. Moving the stop gives the trade more room, but it also changes the risk you agreed to before entering.

How do you make that decision less negotiable? Before opening a position, I’d want to identify where the setup stops making sense, then work out the position size from the distance between my entry and stop. If the stop needs to be farther away, that would mean a smaller position. Simply putting up less margin wouldn’t reduce the price exposure of the same-sized trade.

That’s something I’d practise with small, realistic BTC perpetual positions in demo trading: write down the exit before opening a trade, then record whether I follow it or move it when price gets close. The useful result would be finding out which rule I keep breaking. A profitable demo balance alone wouldn’t tell me that, and simulated money won’t recreate the pressure of a real loss.

I’d also want a rule for what happens immediately afterward. Closing one bad trade doesn’t help much if the next position is larger just to win the money back.

What rule has helped you most with keeping a losing perpetual trade from turning into a much larger loss?