Quick questions.. FTM w/ a 3 week old

1) If baby falls asleep at the breast, how do you burp them? When I try she doesn’t really burp but wakes up and then wants to nurse again. If I don’t try she throws up when laying her down. Currently I try holding her with her head slightly elevated after and then put her down after maybe 30 minutes.

2) She was cluster feeding like every night and now her feedings are lasting longer (about 20-30 mins per breast). She feeds from one, burps, then feeds from the other and falls asleep. Is the change in the length of feedings normal? She’s past her birth weight already so I think she’s getting enough just not sure. 6lbs 6oz at birth, 6lbs 7oz at 2 week check up (dropped to 5lbs 11oz at lowest weight)

3) The latching has gotten easier and takes her less tries but I don’t think i’ve felt a let down. Can you describe what it feels like if you have felt that?

4) My breasts haven’t really changed size again since her birth. Their slightly larger but still can kinda fit into the maternity bras from the third trimester. Is that normal? When does the engorgement occur? Does it not happen for everyone?

Thank you in advance :)