Emotional while breastfeeding

Janet
Hi mamas,
I need your opinion/experience with emotions during breastfeeding. 
When I start breastfeeding/pumping in the beginning I get a strong sense of "missing something/someone" and just a strong sense of sadness but it goes away. 
I don't think it's postpartum depression because I'm very happy with my little one and can't get enough of him, it's just when I'm pumping/breastfeeding.
Anyone have similar experiences?