My 2 weeks old born 35weeks, wakes up every hour last night, nurse for 5mins and falls back to sleep again.. I am wondering if it is bottle confusion, constipation, or just normal for 2 weeks old?

he was introduce bottle in the first few days due to him losing weight and jaundice..now exclusively breastfeeding but sometimes my husband would feed him breast milk I have expressed when I take a nap for max 3hrs. Recently, there's only lil poo but lots of pee when we change his nappy.. Please help me out mommas