feel like im terrible at this

so lately i’ve been so tired id sleep through a pump session a night my baby is only 3 weeks old ive just been so tired and im emotional because i feel like she may not be getting enough, a friend told me she might just be going through a growth spurt but im super scared that im not giving her enough milk and i really dont want to stop breastfeeding i want to do it for as long as a can the goal is atleast her first year im just so stressed do you think my supply will go back up? i feed her every three hours i have alarms set and her doctor said that a 5 hour stretch during night is fine. My supply used to be too much now i feel its too little can i gain it back? advice please ☹️☹️☹️