Fatigue that feels disproportionate to sleep loss combined with difficulty concentrating, extreme emotional sensitivity, or physical weakness warrants a blood test. Postpartum thyroiditis and anaemia are both common and treatable causes of excessive fatigue in the months after birth.
Accepting help with cooking, cleaning, and older children is not a sign of weakness. It is how recovery works. Building a basic support network before the baby arrives is one of the highest-value preparations a pregnant person can make.