Will she sleep with you on the bed? You could try lying down with her then transferring her to the cot once she's asleep. Or just co-sleep for a while till she's more settled then go back to the cot.

You haven't done anything wrong! Your DD is trying to tell you something right now and you are responding the best way you can. My DS had very similar problems at that age and we ended up giving up on the cot - he sleeps on a mattress on the floor. Sometimes we sleep with him, usually he sleeps alone.

Wrapping could help, too.
Get your DH to put her down - seriously. She may have gotten into a pattern of anxiety and not sleeping with you, sometimes it helps to mix things up and get another person to try.