Feeling depression already.

With my son I realized I had postpartum depression a few months in. I told my husband what I was feeling and he said to me I don’t understand depression and I have no sympathy for people with depression. I have never in my life had depression. Now that I’m pregnant again 4.5 months I’m feeling like I’m already getting depressed. As I am super happy and excited for this baby I have no clue why I am depressed. Is anyone else feeling this?