I feel ya. I used to get carried away doubling down as well and lost close to 100k shorting OPEN. Lesson learned, I don't do that anymore and do way better. For me the stress of oversized positions caused further bad decisions. With smaller positions you can just let it ride without having to worry too much, and most of the time that patience pays off.
I didn't listen to those who told me doubling down was stupid either, but maybe you can be wiser than me, without having to learn that painful lesson yourself :D