With the baby born at 27 weeks, I think she will have at least 4-6 weeks to get her supply going. I have never heard of a premie that young going home in a month an a half. Odds are, she will have 2 to 3 months minimum before the hospital cuts them off.
Good luck momma, and I hope you are getting lots of support from the hospital staff and LCs. I think it is crazy that the hospital would withhold a life-saving substance like that, just because the baby wouldn't get it at home.