my baby is 14days today. I also have the same issue as you. I pump every 3 hrs but only got 60ml to 80ml max. if I missed 6 to 8hrs I will have 100ml to 120ml. i watched alot of YouTube videos on increasing supply and the key is to pump regularly. best is every 2 hrs and not missed any sessions. it is hard for me as I will need to monitor my nanny if she feed my baby on time and also after that to pump. so every night I sleep only 2 to 3 hrs in total max. I will have naps in the afternoon though. sometimes I am too tired I will sleep longer. I will feel guilty too, but don't be too hard on yourself. formula milk is good too...all those around me grew up well with solely formula milk as well. at least now our baby has a mixture
The best way to increase your supply is to pump more often. I pumped for 30 mins every 2 hours day and night for nearly a year. I switched to power pumps every 3 hours after that, and pumped extra on weekends. My supply was really low initially, but with time, and disciplined pumping, it got better. I’m planning on stopping pumping this month (I’ve been pumping for over 2.5 years) It’s been a hard road. But so worth it. Here’s an article you may find helpful: https://sg.theasianparent.com/increase-breast-milk/ if you’re looking for more tips to increase your supply.