Sleep - concerns

My baby is 7 sis old and was born on 5 pounds 9 ounces. I was advised by her pediatrician to wake her up every two hours to eat and let her sleep for 3 hours during the night. She usually wakes up around the 2 1/2 hour mark to feed overnight. Yesterday was a long day for her and where she had a hard time sleeping during the day ( she only napped in my mom’s or my arms). She was exhausted and then wouldn’t go to bed. She finally goes to bed around 10:45 and I try to wake her up around 1 to eat. She doesn’t wake up through a diaper change and I decide to let her sleep another hour and try again. She sleeps until 2:30 and I wake up and try to wake her again. She is sound asleep, I undress her, gently rub her belly and touch her hands and feed. I put my breast to her face and she latches ( this wasn’t happening earlier)... I feed her for about 10 minutes and she seems to have fallen asleep again. I I know babies aren’t supposed to sleep more than 4 hours at the time, what should I do in this case? I want her to be able to sleep through the night on the long term, as of right now I want to make sure she’s eating as she should. Am I doing something wrong or is it normal for babies to do this if they’re tired?