My LO was born at 28wks I spent 10wks in hospital in total. I would cap my visit to an hour or 2 twice a day. I would make sure I was there for at least two cares a day. You need to recover as well. I was very lucky on my surgery days my parents would go and do his cares. Mom guilt is a horrible feeling. My LO is 19months old and the only time I have ever left him was in December to have a hysterectomy and my gyane made me stay in hospital for 7 days because she knew I wouldn't rest. Giving birth to a preemie is emotionally exhausting and physically exhausting. Take a day off you will not be judged. You also had a c section you need rest let your wound heal.
My LG was in for 4 weeks and I took probably 3 days off, but when I went in, I usually only stayed for maybe 2 hours in the morning, came back and had some chill time (easier said then done if you also have a 1 year old) and went back for a couple of hours in the afternoon. I was still the person she saw the most and I was pumping etc when I wasn't there but also, you've been through a hell of a ride so give yourself a break! They don't know any different!!!