First baby born at 30 weeks. How to deal with anxiety.

I had my daughter on October 22 and she was 30 weeks gestational age. She's currently staying in NICU and they're planning to keep her until Dec 31st or when she hits what would have been 36 weeks. Everything is going great and she gets stronger everyday but I still worry about her everyday. I cry daily and breast pumping is so uncomfortable for me. Not physically but emotionally. I'm not even sure if that's normal. I feel like a horrible mother at times because i don't think I should be this uncomfortable. I feel so empty now because she's not with me. How have you guys dealt with it? Any advice would be helpful. I just don't want to feel guilty anymore and want to see if people relate.