This is going to be a long one

I am so overwhelmed. I am breastfeeding for the first time with my second child (first was premature and my milk didn't come in fast enough). My 1 month old wants to breastfeed constantly and will scream bloody murder until I put him to my breast. He had weight gain issues and we had to supplement with donor milk and later formula both at the hospital and when we returned home. I have been regularly breastfeeding daily along with formula and recently moved over to mostly nursing with formula at night and maybe 1 bottle during the day if he is going crazy and I'm busy with my 2 year old. I would prefer to get rid of the formula completely, pump and store breastmilk for dad to feed him with, and otherwise nurse. The problem is that when I pump I'm lucky if I get one ounce combined and he is always acting like he needs to eat. It's making me panic that I'm not producing enough for him. When given a bottle he chugs it like I've been starving him. I have tried a variety of flange sizes with limited improvement and take fenugreek and drink mother's milk tea. I have increased my supply some but I still think It's probably not enough. When I can I let him just sit on my breast to increase supply but he will nurse for 45 minutes (he falls asleep but if I move at all he wakes and starts again) and then start again 5-10 minutes later. Is he pacifying? How do I know? I have given him my knuckle which has mixed results. He is peeing and pooping lots and swallowing if sucking. At this point I'm stressed out which is definitely not helping my supply.

I'm starting to feel like I'm just failing completely.