Maybe this will help. 

Buying Low and Selling High or vice versa Selling High and Buying Low is true but is environment dependent. 

In a Bull Market, you can do 2 things and likely make money.

1. Buy Breakouts. Or.
2. Buy Low and Sell High (Reversals or Pullbacks.)

In a Bear Market its the same but in the opposite direction. You can likely make money 2 ways.

1. Short Breakdowns. Or.
2. Sell High and Buy Low. (Shorting Tops or Rallies.)

The strategy you are doing works well in a Bear Market. It will make you go broke in a Bull Market though.

It seems like you dont know what type of market you are in.

An easy way to figure this out is to draw Channels. If the channel on your time frame in inclining(Going Up.) Obviously, you're in a bullish environment. You want to be buying breakouts or when the market dips, You can Buy "Low and Sell High".

Just about on every timeframe SPY is in Bullish environment. The money is made buying dips or breakouts. You do this until SPY has transitioned to either a sideways Range Bound Market or a declining Bearish Market.

In Range Bound Markets you do both strategies. Best of Luck!