When Kate Arquilla gave birth to her second baby, she didn’t anticipate how much her new daughter’s arrival would change everything. “I was trying to balance caring for a newborn and a toddler who were just 17 months apart,” she tells SELF. “At times, I would get really frustrated and it came out as anger—and almost rage.”

Arquilla, 34, recalls a time when she was trying to feed her newborn and her toddler was climbing all over her. “He started to have a tantrum—totally normal for his age—and I started yelling,” she says. “I was so angry at the situation. I wasn’t feeling right, but I didn’t know how to verbalize how I was feeling other than yelling.”

As a neonatal intensive care unit nurse and the founder of Bumblebaby, a Chicago-based group that specializes in services for new parents, Arquilla has spent much of her career working with people who have experienced this exact situation. Despite this—and the fact that she was already familiar with the emotional roller coaster that naturally comes with parenting—the anger caught her off guard. “My mood was off,” she says. “I was either really low on energy or irritable and angry. And that’s not my typical personality.”

It wasn’t until her therapist put a name to these feelings that her experience started to make sense. She had postpartum depression (PPD). Arquilla’s PPD manifested as anger—an emotion that carried a lot of shame for her at the time. “My kids were healthy and happy, and I felt a lot of guilt for not loving every moment of motherhood,” she recalls.

Learn more about postpartum anger and resources that may help in the full article at Self.com.