Feeling anxious and upset while breastfeeding is a D-MER symptom. When there’s a rapid release of Dopamine and Serotonin, this hormone change can linger even after the minute D-MER presents itself. For example, I had it so severe that it took me longer to recover from the let down. In addition, since I had to breastfeed every 3 hours, by the next time I had to breastfeed I was still dysregulated.
I've actually started to notice this too! I just thought it was due to being tired maybe but yeah only happens while breastfeeding so maybe!