Why do you want to introduce a bottle?
Just asking. Many mums feel they have to, for various reasons, let others feed, dire warnings that you’ll never get a break or leave the house, for childcare...
Firstly 3 weeks is early. Give it another few weeks until your supply is settled and you’re confident in your supply.
Fwiw I found bottles an utter pita. When you give a bottle you have to pump instead, to keep up supply, to stop your discomfort, reduce chance of mastitis etc. So while someone else if sitting cuddling and feeding your baby, you’re washing, sterilizing and pumping. Twice the work for each feed you replace with a bottle.
Second some babies like bottles as they don’t have to work for letdown. They’re less fussy with bottles, and it can seem like they aren’t getting anything from the breast as they fuss and then guzzle a bottle. It’s just easier, except it can be misinterpreted as a supply issue. Same with expressing, some people just can’t, and again it makes you worry about supply. Expressing isn’t as effective as actually feeding as well, so it can affect supply.
Not to say it’s can’t work, of course. But I pissed about with bottles with my first, it was hard work, stressful when I couldn’t express, baby preferred bottles and would fuss the next feed, and to top it all off we got to 4 months and she started refusing bottles completely anyway.
Second I just fed. Lot less work, i wasn’t having dh sat on the sofa while I ran about. So I fed, and he got me tea and snacks. Also stopped visitors insisting in feeding while I ran about getting tea and biscuits...