Hi, welcome back to the forums

I don't have any experience of using BW at such a young age I'm afraid but when I started at around 8 weeks I used to just aim for one nap a day in the cot, and I had to sshh pat all the way through it, pretty much, so what you're describing sounds quite typical of a 3 week old to me

Babies have an A time of around 1hr at this age (
Average A times- BOOKMARK ME! ) you could try aiming to have her asleep by then for one nap I always found mine went down best for the first one of the day. I'd AP the rest and enjoy the cuddles to be honest

The other thing I'd do is keep an eye on the potential reflux. I don't know much about it but if she is refluxy you will probably find it very difficult to establish a routine, even if you're doing everything "right". I don't know at what age Dr's would diagnose reflux, but you can probably start trying to figure it out yourself and gathering evidence to take to your Dr. The following link may help:
Reflux 101 - General reflux informationFinally, getting to know your baby is probably the first step in establishing independent sleep and a routine. Does she like more or less A time than average? Does she like a long wind down for naps / bedtime or none at all? Does she like sshh / pat, or just the sshh? While you're enjoying your newborn cuddles, you can start getting today know her, and when you're both ready for more concerted sleep efforts, you'll already know a bit about what she likes and what works for her. This links may help if you haven't already seen them:
The BW "Know Your Baby Quiz"The Five Types - Everyday MomentsRecognising a Baby's Cries