It's not about "S/R levels" as most retail traders use the term today; it's about those levels at which important traders buy and sell. These generally have nothing to do with what retail traders draw on their charts.
As far as knowing what the market has already done, that's the point. At what level do important traders take profits? At what level do important traders re-enter the market? If you've never looked at this, I suggest you do so. At the very least it will enable you to take a bigger chunk of your profits out of the market rather than just sit there like a deer in headlights and wait for price to sink to your stop.
What are you doing to know where important traders are taking profits?