Unplanned pregnancy

This is my second pregnancy (my son is 21 months) and I'm feeling all types of overwhelmed. My husband was planning to get a vasectomy soon and we found out yesterday that we're expecting. We have decided to go through with the pregnancy but I'm just so exhausted already and I still currently breastfeeding my son so I'm worried I'll have to cut it short. Anyone else feeling extremely overwhelmed and have some worries? I'm hoping it gets easier.