Latching, milk supply, pumping, cluster feeding & finding what works for your baby is a process of learning. Give yourself grace because every breastfeeding journey looks different. 
With my daughter being a late-term preemie, we had to be extra mindful of her weight and make sure she was getting enough milk. A lot of moms ask, “How did you know your baby is getting enough?” Honestly… I didn’t. The lactation nurse gave me some great tips that worked out well for us and gave me peace of mind. Here are some things I learned along the way that I hope can help another mama.
Newborns, especially those first few days, get tired so quickly and fall asleep while feeding. Here are some things that helped us:
First and foremost, I’m sure you’re tired of hearing it but buy a nursing pillow! This was a must for my back, posture & helping baby get into a good position. Remember, you’ll be spending a lot of time feeding while you both learn.
If you’re worried about intake, weigh baby before and after a feed to see how much they’re transferring. (Just make sure they’re wearing the same thing both times — no extra socks, onesie, or burp cloth — so the measurement is accurate.) — also Momcozy has a scale for weight and height 
after every latch we also had x amount of expressed milk/supplementation to make sure she was getting the amount she needed every 2–3 hours to support her weight gain. Since she also had jaundice, keeping her feeding was especially important for us.
If your newborn starts getting sleepy during feeds, try gently taking off a layer of clothing, rubbing around their ears, or moving their arms in little circles to help wake them back up and continue feeding. (All three methods worked) 
Every baby and breastfeeding journey is different, but I hope sharing what helped us can support another mama who may be feeling worried.
thank you!