Look up D-MER... Dysphoric milk ejection reflex. It is not common but yes it is a hormonal response. It's true that oxytocin usually makes us feel happy and relaxed but for some women the letdown causes an empty homesick type feeling instead. I'm sorry you're dealing with thisMaybe try posting on the bf forum? I'm sure there must be other women who are dealing with D-MER and can offer advice or support.