I was in awe to read your 'births' story (hey, we do it twice or more right, i like to take credit for this ) and so grateful you made it through mama
(((I think you have an edge of experience on almost all of us, so no one can really get how you're feeling in terms of your recovery)))
My twins were in hosp for 4 weeks, we came home with one b'feeding at 36 weeks, and one tube fed with some breastfeeds. She was and still is slow to gain weight but meeting all her other milestones. I used pacifiers between 5 and 10 months because that was the window that they would take them. giggle. As long as you watch that you're not using them to extend feeds like crazy and their gain is fine there should be no worry.
I do remember I sat and nursed on cue for 12 months before I started to try and regulate feeds a little. Mine were not slow feeders once they got the hang of things (only 20-40 mins p/nursing). The first couple months were intense but they passed. I remember freaking out once though and going for a half hour walk round the block, leaving my dh with two not so happy babes
I home ed my older four children and decided we could do more with babies attached to the breast than with a mommy who had to sterilise, prepare and pay attention to bottle feeds, so even though I had times of touched out overload, I feel breastfeeding was the easier option by far. I would also say to you: don't bother to express - if anything ever happens and you needed to be away in an emergency, they would cope. Someone would find formula and get through that time. It would be fine. Pumping could just make life unnecessarily complicated. If you really need the security of pumping (I can understand that, I did it for a while as was so used to it being the only means of food for them in SCBU and I didn't like an empty freezer!!), then go for it once a day in the morning and your supply will steady at that level of production.
Also agree with PP's that tandem nursing saves time and energy and baby with weaker suck gets to benefit from let down of the stronger twin. Woo Hoo! Bonus!! I loathed it mostly but it served a purpose
Have you looked for tongue tie in Matthew? Sometimes can cause a better latch one side than the other. How is his palette? Any moulding on his head that cranial osteopathy could help with? You can also use breast compressions to increase milk transfer for them both. Just squeeze the back of your breasts gently.