The problem in your setings is that buy level is set to 4.
This causes the strategy to only buy when:
- price is 4% lower than the lowest EMA (which will happen seldomly!)
- AND price is 4% below the lower bollinger band (as set in LOW_BB)
Drastically decrease buy level (can even be negative, if you want to ignore EMA) should make your strategy behave as your expected.