I gave a bottle of ebm at 3 weeks in the evening as a top up after a feed from a tommy tippee closer to nature bottle. No problems at all, ds will happily take a bottle now and it has not interfered with breastfeeding in any way for me. I was advised at the local breastfeeding support cafe to wait til 6 weeks but I'd already started expressing and was having no problems so couldn't understand why I should wait. I know people who waited and have struggled to get baby to take a bottle.
christiana, I do feel for you and you have summed up exactly how I felt - I'd sleep with DS latched on but wake startled and frightened that was he was there. But I did get used to it and went on to co-sleep for 18 months. You are also probably sleeping lighter than you realise with her there.
I'm not saying that is for you necessarily but that the initial shock of sleeping with them - you can get used to it. Could DH watch over you for a night or two so you do get that rest but can relax a bit more? Is there anyone who can help you in the daytime to get a bit of sleep?
It just sounds to me as if your problem is just being knackered with a newborn (I don't say 'just' to trivialise, god no - I shudder at the memories, it is very real and valid and awful) rather than a problem with feeding. Can you follow the old 'sleep when she sleeps'?
I would certainly introduce a bottle as soon as possible. I only introduced a bottle at 6 months, when I was returning to work. That was difficult because she was to used to being breastfed. I did read somewhere that you should introduce it by 6 - 8 wks if you intend to use a bottle. I hope it all goes well.
Oh I understand that, well we only have one DC but slept apart for a while so he could at least have a bit of energy.
I think laying down can be as good, no tv/laptop screens, no noise, close your eyes, don't think about housework or day to day chores...
I don't know about the supply thing really - I have read Tiktok say (paraphrasing and just hope I am remembering right, apols Tiktok if not) that supply can 'dip' but tends to be more temporary, perhaps when stressed etc. But that it certainly shouldn't be a problem as long as frequent feeding etc is kept up.
I have to admit I was quite naive when feeding my DS and I look back and think it's a wonder we ever got it established. I don't ever remember thinking he was feeding for too long but he did feed all the time - in all honesty I think I as just glad a) he wasn't screaming and b) I got to sit down But I do think it can be a fragile relationship in the early days and it must be double the challenge with an older DD there as well.
If you are able to express in the morning there is no harm is there as long as you don't miss a feed, I doubt it would harm your supply to have an early night I would just worry about replacing a breastfeed as routine, IYSWIM.
Oh and re bottles, well I introduced one at about 2 weeks but he did then refuse it by 6 weeks anyway so I don't think there is a hard and fast rule over timing being right, if she is stubborn she might reject it at any age, or take it happily...
Oh and don't discount the possibility of a growth spurt, isn't there one at about two weeks? She may just surprise you and settle down a bit in a couple of days <hopeful>