lots of sympathy furry. you must be exhausted.
I think some of your answers are right there in your post
you went back to work and she has reacted enormously. She doesn't want you to leave, and when she does fall asleep and wakes up again and you have gone she screams.
When you bring her down stairs so she knows she has your attention, she is happy.
I say all that without judgement. Life is just the way it is sometimes, and it helps to see it a bit objectively
I would say there are 2 issues here, and without knowing you or her, I wouldn't like to say which is the more relevant
- she is afraid that when you leave you won't come back, or you won't come back for a long time
- she wants your attention and she knows that by screaming and crying she will keep getting it. She hasn't had it during the day, so she will get it any way she can now.
The harder thing is finding a solution. Not sure what your working hours are or if you have a DP to help, or or what childcare you are using.
Can you work it so that when you come home, you have some time with her, playing talking reading, cuddling and so on? Look agian at bedtime routine. Make a clear routine that suits you (eg bath story, cuddly and bed. One song and then sleeptime)
Can you bear to do controlled crying? I sya that because it looks to me as if she is screaming for attention, and I think you need to stop giving her all the fuss at bedtime. Go back to where and how she slept before (eg cot, with bottle) and have one or two nights with controlled crying to re-establich her routine. But I would only do that if she has had good time with you before bedtime.
Also don't underestimate how much she can understand. Mummy is going now, I will be downstairs. Mummy will be downstairs if you wake up. Mummy isn't going out, I will be downstairs etc.
Not sure if any of that is any good. just didn't want ot leave it unanswered