Welcome to Mn and congratulations on your lovely new Dd
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I wonder who is telling you this and are they offering any practical support like getting your lunch and taking dd for a bit while you have a bath? If you do want to help her distinguish day from night then try to get her outside at least once a day and keep things light and bright in the day and dark and quiet at night.
What you are doing is perfectly normal and most people do what they need to do just to get through the night.
Your dd has spent 9 months tucked up inside you, it's natural that she wants the warmth and comfort of you, which you are providing. Give yourself a huge pat on the back and have a
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Putting her down when she's crying won't teach her to distinguish day from night, what it will teach her is that your not there for her when she wants you. If you continue seeing to her needs, she will cry less and by, I think its about 7 months, and be more secure.
It's all so new at the moment, you can't cuddle her too much but you can cuddle her not enough. Things will change and they'll change again.
If you want a bit more reassurance, have a read of this on normal infant sleep 
Haven you tried feeding lying down too? You night be able to get some more rest that way 