Two and half month old / feeding query.

My baby girl is two and half month old. Her birth weight is 2.67kg (one month preterm). I am breastfeeding her exclusively. Now her weight is 4.9 Kg. From past few days she is drinking milk only for 5 to 7 minutes. She is sleeping 1.30 to 2.30 hours in the day time after feeding. Also in the night she is awake and often crying from 9.30 pm to 1 or 2 am daily. At that time i need to feed her two or three times. After that she is sleeping continuously for 3.30 hours to 4.30 hours straight. Is it normal? She is passing urine more than 8 times a day. Pooping every three days once. Also I have another question, sometimes when she is lying in bed, she is giving some strange sound like she is trying to cough and sneezing often without having cold. Is this normal?