As everyone has said, you are doing it wrong. However, if you want to persist let’s see a side on photo of the derailleur in small-small and the same angle photo but with the chain off (so no tension) on the derailleur. You could also tell us the range of teeth on the chainrings and cassette.
Mine may nor be the best approach so I'm open to suggestions.
Here's how I roll.
So I'm hurtling down a big dipper (30% both sides) trying to get as much speed up as possible so that I can have decent momentum going up the hill on the other side of the dip.
Near the bottom, I flip down to the small on the front but stay small on the back so that I can apply some welly at the start of the uphill section.
Being already on the small on the front avoids me having to use the front to shift down when the bike is under load when climbing.
As I climb the uphill section, I progressively shift down on the back.
Any advice welcome.
BTW. I've just taken off the chain and the derailleur doesn't fold back up in on itself like it normally would with the chain off. The spring action seems pretty weak (virtually zero return force when pressed against).