Milk supply for nicu baby

Mr

I'm not sure if this belongs in here or breastfeeding but my baby is currently on week 5 in nicu. He was doing amazingly with breastfeeding until the doctors decided he needs to have two bottles a day with added human milk fortifier for his weight gain. After each time he had a bottle it was a fight to get him to breastfeed again and then he wasn't satisfied afterwards. I made the decision yesterday to have him solely on bottles, it was one of the hardest decisions I've had to make as a mummy but it's what's best for both of us right now, it was taking it's toll on me emotionally and mentally having to fight to get him to feed and then top him up with a bottle all the time. My issue now is I have quite a bit of ebm to last him a little while as I was expressing huge amounts when he was being fed through an ng tube which is great, but my supply has dwindled a lot because the supply and demand for him wasn't that great. I'm trying to express regularly again but now I seem to be getting less and less every time to the point where I'm only getting around 30ml each time from both breasts combined. I was getting 130ml + from each before. They've said the more I express the quicker it will come back but it's just not happening. Is there anything I can do to increase my supply again aside from drinking lots and all the other obvious things? I want my baby to have my milk even if he cant get it from me and i want him home asap, all he needs to do is gain 240g.