Hi there hun, hugs for the hard time ATM. I think at this age LOs can learn that if they keep up the crying long enough you will cave and they play on this a little. I think GW would work really well for you, we used it with our DD and she has been a really great sleeper since.
So here to hold your hand if you like and offer advice if I can. Can you put your DD in her cot awake for naps/BT and stay with her or does she scream straight away? What you will probably need to do first is put your mattress right by her cot. Do your usual WD and then put DD in her cot, using your sleepy phrase like "it's sleepy time now, it's ok mummy is here". Then lie down on the mattress but rub DD's back or pat her, whatever works to calm her but try to avoid eye contact, conversation or PU. You can keep repeating your sleepy phrase over and over or shush, but be as boring and lifeless as possible. Now there will be crying but remember you are right there with her all the time and she will be angry not feeling scared or abandoned yk? I can promise that eventually she will get fed up and lie down and go to sleep. It took us 40 mins the first night, not crying all of that but on and off.
If she stands up use your sleepy phrase and add "lie down" but let her get on with it. If you PD it may become a game or get her really mad. Basically try not to be drawn in by the antics that she may try. I had dummies dropped on my head and teddies thrown at me!! I just put them back in the cot through the bars with no reaction at all. If your DD NW repeat this back rubbing or patting back to sleep without PU if possible.
After a night or two of this, lie on the mattress but try to take your hand off once DD is calm and only put back if she gets upset. Next night lie on the mattress but calm only with your voice and sleepy phrase if you can. From then on you can start moving the mattress further away each night towards the door. Eventually you will be able to walk out of the door and DD will settle on her own. HTHs sorry it is do long! Good luck and any questions just ask.