A Sad Day - History Repeat

Stop loss once again is my weakness. The expected loss finally came in today when market unexpectedly made a 15 point dive at 1:25 - 1:33. I had entry average at 1555 with a slightly bigger size (2x). I should stop loss at 1552-1550 area, but that'll result in a big loss. So, a sad history repeated itself, I average down all the way to 1542 with huge size ( 6x) and huge unrealized loss. Luckily, once again, the market came back to my AD point 1550 and I was able to make out without loss.

But, this is sad that once again I fell into a big hole. Lucky my trading size is not big right now, so I could AD. Imagin what'll happen if my first position is full margin. I need to think about this.