Switching from breastfeeding to formula

I have been having a VERY hard time breastfeeding my first child. He will be 1 month old next Friday. I have tried everything and worked with lactation consultants to try to increase a very low supply and nothing is working so I am looking to switch to exclusively formula feeding. We have had to supplement since he was born so he is used to getting breast milk and formula. I do not pump because everytime I did, it would be maybe 2 or 3 drops from each breast after each 20 minute session. Not enough to try to put in bottles to help the transition. My question is, how to I stop my milk without becoming engorged? Also, how much formula should he be getting? Please no comments about things to try to increase my supply or how I'm a bad mother. I already feel guilty enough as it is. I have been at this for a month and my son lost a lot of weight in the process. He is now doing MUCH better with the supplementation so I am interested only in how to transition myself and how to feed him. Thank you!