@xuanang01 I started bed sharing before my baby (now 9 months) was 2 weeks old. She is a great sleeper, but every bassinet (tried several different kinds), pack n play and crib, did not work. She would not stay asleep. But if I put her on our (much more comfortable firm bed) she'd sleep soundly for hours and fall asleep on her own easily, without being near me. I tried so hard not to, even though I knew that developmentally it's what babies need and want and the majority of the world does it, but I fell asleep sitting up one day, while holding her, and almost dropped her (dropped her down to my lap and thankfully I woke up).
To this day all I really have to do for naps is lay her down, put her pacifier in, and sit or lay next to her for a few mins. Then I leave and she sleeps fine on her own. At bed time she goes to bed like that at 7 pm and I don't go to bed till 11 pm. I have never had to rock her, shush her, hold her, etc. because she learned to fall asleep laying down next to me. And if I am holding her and she wants to sleep she struggles to get out of my arms till I olput her down on our bed, then she lays down, opens her mouth for her pacifier and goes to sleep on her own.
Follow the safe sleep seven, look up a floor bed (so you don't have to worry about baby falling off your bed), and do what your baby needs and wants.
BTW, I'm an early childhood educator, child development does not jive with sleep training, so I would never do it and I don't know anyone in my industry who has either. Also, sleep training is super privileged so definitely doesn't work for a lot of families, they deserve solutions they work for them.
Edit: typos ans clarification