How long does it take for breast milk to completely dry up if you don’t breastfeed?

I was in a similar situation where my son had awful reflux. I breast fed what I could for the first month but was only able to pump 80ish mls every 3 hours so not enough the other feeds were a reflux designed formula and honestly since switching completely to formula he has gained weight like a champion and he is a happier baby. Don’t feel guilty for doing what you needed to do to keep your baby fed. On that note even there I didn’t ever establish a full supply I’m still able to get a very small amount of milk by hand expressing 4 months on.

There are formulas designed to help with colic also. If you have TikTok there are a few videos on relactation journeys and it is possible but can be very draining

I would recommend you see a lactation consultant to help you on this journey. You’re still pretty early pp so it may be easy to re-lactate but you need some support. I struggled a lot with breastfeeding at first and an LC was my saving grace. I spent way too much time and money trying to figure it out solo and I wish I had sought help sooner.

It usually takes longer than a lot of women realize. Definitely suggest an LC especially one who specializes in pumping. You'll need your flange size checked for sure and to be taught how to use the pump properly.

It won't be easy. You'll have to pump almost around the clock to stimulate your milk supply and increase it. Really think about what you want as you may feel like all you're doing is trying to make milk.

Can take months to years in some circumstances x

It's not too late! I gave up breastfeeding around 2 weeks PP for almost 2 weeks because i simply couldnt handle it. but like you, i wanted to try again because it felt right and i was missing bonding with her. i believe you can get your supply up and more than enough if you dedicate yourself to it and be patient too.
what helped me get my supply up were doing at least a few of these things daily : Liquid IV, powerade, body armor, instant oatmeal, power pumping, pump in between feeds, mothermilk tea, breast feed on demand + formula until the supply is established, and visiting WIC lactation consultant. also i believe watching other woman with an ample supply is helpful to believe it's possible for you to have a great supply

it took me about a month to go from under supply to over supply which requires me to pump in between feeds sometimes. i hope some of these helps!