Many thanks for all your very helpful feedback, really appreciated it... will read the replies again and again to understand better. Glad that I posted this thread.
Basically I scalp es with KD, volume and average price, I don't know what constitutes a trading system, I rely on feel a lot and don't have definite entry/exit signals, maybe it's just a trading method. I only trade outside the regular trading hours before this big loss. At the beginning of every trading day, I evaluate the overall trend of the day, if I think it's bearish, I will do more short selling.
Some of the errors I made and rules I broke:
1. Trade with my phone. Sometimes I trade while I'm outside. e.g. in restaurant, I thought it's fun. This time half of the trades were made while I was sightseeing, the biggest loss was over $600, I had a chance to get out with a small profit after I got home, but obviously I didn't have the correct feel about the market just by glancing at my phone every one hour. I think this is why I didn't take the chance to get out immediately.
New rule: only trade when I'm sitting in front of my desk. Trading should be serious and focused.
2. My evaluation of Friday's market is "could be very bearish", I should go short for most trades. For long positions, I should cut losses very quickly and no avg down. This is a rule I broke.
3. I had 7 winning days in a row, and the previous day was a lucky day, I settled for $90 profit because I think it's a dangerous day. Friday is more dangerous but somehow I took it less seriously. Usually after 4 or 5 winning days, I will tell myself a big loss is coming, it's wise to stop trading for one day, or must be very careful.
For now, I have set up $300 as my game over loss, I will have more losing days, but it should be better than a big loss. I have subscribed to button trader to enforce risk management, but I'm not sure if I will use it as my primary trading tool, I can't get used to its UI.
Can you see yourself in operating room with brain surgeon, he bought the cracked glasses at dollar store cause they were cheaper, he is going to check out the hospital in between working on your brain, he wants to check out new nurse on 3rd floor, so he quickly does something to your brain and your right leg is now pointed to the ceiling bleeding out your brain but surgeon is having a convo with new nurse, HE is sightseeing. Unless you treat trading with respect and as a business, there is no place cept going down, only one who can enforce anything is you.
When you have made enough money for two lifetimes, then you can become eccentric and trade off smoke signals, people will think you are quirky, that will last for your 30 seconds but in mean time, this is your business, run it that way.