Hi Leigh
Congratulations.
Sorry don't know about mastopathy but I do know about type1 diabetic on a pump with a child in neonatal unit and expressing.
My eldest (2 next week) was in neonatal unit and I expressed for her but found i didn't have much milk supply and stopped by around 4 months of combination feeding. She couldn't latch either so I couldn't stimulate supply that way once she came out.
I have just had twins last month and my little boy went into intensive care for a month (just come home) and his twin sister had to be ng tubed for about 10days before she started demanding feeds. She wouldn't latch and because I was concerned about her blood sugars I opted to give her formula (my eldest had no blood sugars).
With everything going on I didn't start expressing until about day3.
Anyhow as we were in separate hospitals with my twins (nightmare) I expressed at both hospitals. They would set up screens and pumping for me next to my little boy whilst he was in intensive care etc. I have also tried to drink loads of water this time.
I am 5w after having my twins born at 35w and my supply is good from expressing now-neither twin could latch. I did hire the hospital grade pump which I think has helped. I am combination feeding by bottle my twin girl and mainly giving express to my little boy as feel he needs it more.
Whatever happens you are doing the best for your son. I felt so guilty with my eldest about not being able to bf her and ended up in tears but you are giving him something.
Make sure you pump regularly at least 8-10 times per day and at least once between 1-5am, drink lots and lots of water, try and relax and not get stressed.
Good luck from a fellow pumper!!
x