I wouldn't sleep train... I've done a LOT of reading on it over the last few months and I'm dead against it. I've read a lot of articles/studies about how sleep training is more often than not only effective on a short-term basis - if at all - and it can have detrimental effects on the baby. A study done in 2012 showed that the cortisol levels in the baby remained elevated after they had stopped crying - so basically the baby is still just as distressed, they've just learnt that nobody comes so there's no point in crying.
https://www.peacefulparent.com/sleep-training-research-highlights-the-myth-of-self-soothing/
Babies are meant to wake frequently; it's how they're built. They are physically incapable of self-soothing, so trying to 'train' them to do so is futile! Some people are lucky and get babies who don't need as much parental input as others to get to sleep. This is not synonymous with 'self-soothing'. The part of the brain required to self-soothe is not yet developed in infants. Again, many people believe they've taught their babies to self-soothe - this just isn't true! They've simply taught their babies that they won't (always) respond to their stress signals.
Here's a good quote I read on it.. "Through sleep training you can condition a baby not to cry out for attention and go to sleep without parental input fairly easily, but this behavior is not indicative of a baby who is calm, soothed or settled."
I think a lot of people have unrealistic expectations of babies and their sleeping habits, and it's based on what they're told, usually by healthcare professionals! Over 60% of parents believe their child has a sleep problem...so surely this isn't actually the exception to the rule, and it's just normal behavior for babies?? People are told their baby
should be sleeping through by however old, they no longer need night feeds by whatever age.. it's just not true. Night wakings are so much more common than you would ever be led to believe. I'll put some links to some interesting articles at the bottom here in case you're interested..
Sorry, I don't want to seem like I'm getting on my high horse, and I certainly don't mean to pass judgment on anyone else, I just hate the idea of people turning to sleep training because they think it's a natural step in the process. It isn't! Babies wake through the night and need comfort/milk.
I know this isn't what you want to read when you're asking for advice on getting your baby to sleep when you go back to work though! All I can say is your OH will probably find his own way of comforting her and getting her to sleep. Obviously it'll be completely different to you being there and nursing her to sleep, but it'll all fall into place.. There might be a few rocky nights, but so long as your OH is there to comfort her she'll be fine.
I wouldn't bother too much with the dummy... my DD is the same. She's never really been bothered about them until she's pretty much asleep anyway, and even then she can easily do without. It might be that she takes a dummy when you're not there? Or even a bottle? Do you use white noise? And does she have a "lovey" type thing?? Like a favourite blanket or something? If not you could try and introduce one. Carry it around with you for a while so it smells like you, have it with you while you're nursing so she associates it with that comfortable, familiar feeling. I've heard of people having a lot of success with this.
I feel your pain as I just went back to work last week and my DD won't take a bottle either. OH has tried her a few times with it and she's outright refused it. I've only been doing short shifts so far but I've got an 8 hour one on Saturday and OH is in work so it'll be my mum looking after her, so I'm just hoping she succumbs to it and has the bottle or she'll go all day without any milk!
Anyway, you're doing amazing, carry on and everything will work itself out!!
https://www.pinkymckay.com/when-baby-sleep-training-goes-wrong-the-risks-of-controlled-crying/
https://sarahockwell-smith.com/2015/05/14/ten-reasons-to-not-sleep-train-your-baby/
https://evolutionaryparenting.com/educating-the-experts-lesson-six-the-newborn-sleep-problem/