Oh 3 in a bed is fantastic It explains in there how it helps bf (as I can't remember off the top of my head!) Something to do with being able to bf in their sleep and that stimulating your production I think. But also for practical reasons - you get more sleep so are less tempted to ask your partner to take over night feeds (with a bottle, obv!) for a night. This is my theory anyway.
I am not sure about swaddling. I have a feeling that you and the baby both need to be able to move freely for your protective instincts to work, but I am not sure. DS never liked being swaddled so we didn't have that issue!
When he was tiny, he slept in a vest + sleepsuit and I folded a cotton cellular blanket over so that it was 3 or 4 layers and tucked that over both him and my midriff. I had the duvet over my legs and wore a towelling dressing gown over my upper arm to keep that warm. It was winter though so you might be alright with long-sleeved pyjamas and the blanket + duvet combination.
You need to have your lower arm out horizontally between the baby and the pillow, to stop her wriggling up and getting stuck underneath them. The positioning generally works as so: Lie down on your back on the bed with her on your tummy. Put one hand on her back to hold her on you, and roll gently onto your side, so you are lying side-by-side. (There is a pic on my profile of the sort of position, except DS is facing the wrong way, you need to be tummy-to-tummy.) Then you need to shuffle her downwards until her nose is level with your nipple. It seems FAR too low down, but don't worry. Use your upper arm/hand to pull her bottom and legs as close as you can into your body, which should give her the best angle to feed in. If you can brush her top lip with your nipple, do - this should get her to open her mouth and latch on. If you can't reach then just poke the nipple around near her nose(!) and she should smell the milk and try to latch on.
DS tends to nap in the daytime wherever - on the sofa, usually, or on the floor, or in his bouncy chair (getting a bit big for that now, but fine for napping in) - or the buggy or car seat if we are out. What kind of sling have you got? DS hates any which lie down in a cradle hold but loves any which are upright.
As for going to bed at 7.30 - DS tends to go to bed at 10 or 11 when we do - but if you want your evenings to yourself or you need her to get up early, the best solution is probably to co-sleep part time, where you put her to bed in her cot or moses basket and bring her into bed when she wakes for a feed in the night. Means you only have to be awake for about a minute! We found that we could take one side off our cot and it is still sturdy so we have done that and pushed it up next to our bed to make a bedside cot. So if DS does go to bed before us, I put him in the cot and then when he wakes in the night to be fed I just scoot him over into the big bed with me. Sometimes if I am still awake at the end of a feed, I put him back into the cot.
HTH, sorry it took so long to type, I got distracted...