We gave our DS one from about 6 wks. He wanted to suck all the time (for comfort like your DD) so it was a lifesaver for me. It didn't interfere with BF at all. We also preferred that to thumbsucking. If his thumb drifted towards his mouth, we'd remove it and replace it with a dummy. Now, he only has it to sleep.
Same here. It really was a lifesaver. I hated it at first but you know what, if it offers comfort to my baby then why not?

We use the Avent ones. They are gorgeous and didnt interfere at all with bf, I bf her until 11mths. I actually got a dummy chain as I have a child that chucks things that arent attached! Also when she got a bit bigger, it is easier for her to find in the night when she wakes as she just feels for the chain and then picks up the dummy and put it in.

If I havent put it on the chain then she often wakes up in the night or from a sleep early as she cant find it to help her resettle.