low breast milk supply, pls help

am a first time mom. my baby boy is a month premature and he was in the NICU for a few days. so it kinda disturbed my plan for exclusively breastfeeding since they used formula for him while in there. however, I plan to switch him completely to breast milk, but unfortunately my breasts arent producing enough milk. they suddenly stopped supplying more milk. i nurse every 2 to 3 hrs, but still the breasts arent responding. my baby nurses hardly for 5 monutes on each side and he stops latchinh on since he isnt getting any milk. this wasnt the situation last week. any tips to increase the milk supply? please help. i feel so bad for not being able to supply him with enough milk, its one thing that makes mom so unique to the baby and am miserably failing at it