NICU EBF & 2 neosure bottles: when to introduce bottle?

Holly
Hi, 
My daughter is a preemie. 3 weeks (35 weeks) on Monday. Breastfeeding is going great!! She latches & averaging about 20 m a session. 
Here is my struggle. They asked about introducing bottles. I'm terrified to start bc bf has been going so great but i know she will need 2 neosure bottles a day so we will have to introduce at some point. Has anyone had this experience & still had success with nursing? Did it go downhill after introducing a bottle? Is it possible to back to ebfing? Just looking for any sort of guidance. 
Thank you!!!