How do you know when to stop if you have low supply?

I need low milk supply advice please.
 
My 5w old baby's in NICU. He has about 8-10 weeks to go. I've hired a hospital grade double pump for home since day 1.
I've had every bit of advice possible from lactation consultants, midwives & doctors and even take medication (Domperidone), but I only get around 1 fl oz (US)/ 30ml a day total.
 
I'm told this is the most I'll get as my milk output/ supply will have definitely been established by now, in fact by at least a fortnight ago.
My baby has 12 feeds a day, around 17ml currently. This is increased by 1-2mls a day, i.e. by tomorrow night he may be having 18 or 19 mls a feed.
 
At what point do I balance up pumping every 3 hours and renting the pump, washing & sterilising all the attachments and stressing a bit about it? My gut says when one of his individual feed amounts (he has 12 a day) exceeds my daily output, i.e. when he takes 30ml per feed, so basically the end of the year.
 
I feel like I can direct the energy towards something else with him or self care. Or getting his things at home ready as we were surprised with him being 14 weeks early.
 
Has anybody been through this or works in NICU/ lactation/ as a midwife?