Hi RachelsFirst - at exactly the same age we used the Baby Whisperer Pick-up/Put-down method, which involves picking the baby up when they cry and putting them back down again pretty much straight away (and repeat until they stop crying). I don't want to mangle the instructions (it was a year ago now) but you can get the book cheaply on Amazon new and used, and it's very useful. It doesn't work for eveyone, but if your baby is an escalating crier (i.e. won't cry down, but gets more and more upset if you leave her) then this is great. DD has slept through reliably since then.
I can count night wakings in the past year on the fingers of my hands, and even if she wakes up a little upset we sometimes hear her cry for a moment and then settle herself again. When we put her down for the night she chats to her toy fox to get herself to sleep, sometimes for up to half an hour, but never usually needs us to help. Also worth trying to see if there's a soft toy she might become attached to - our dd had 'Foxy' from a similar age and the combination of him and PU/PD worked a treat.
I also went back to work when dd was 6 mo, and I must say at 4.5 mo I did wonder how on earth I would cope, but things settled down a lot in a very short space of time. Probably a combination of a number of things (using PU/PD, having a cuddly toy she got very attached to, weaning and just getting a bit older). I stopped night feeding at 4.5mo, as, like you, I didn't think she needed it (some babies do, of course, but I was pretty sure my dd wasn't hungry, just wanted company and couldn't settle herself)
Incidentally, she cut her first tooth at 5 mo, but even when she was teething, once she'd learnt to sleep through it rarely disturbed her - she's just gone through a bad bout (16mo and cutting molars) and she still didn't wake.
Good luck!