I pump as usual while on my period. The swelling typically isn't as good (progesterone is at its lowest at this point in the cycle), so if I don't get around too it, I don't beat myself up about it.
I don't see how suction on your breasts would affect your hormones. Noogle works on the concept of tissue expansion and is not doing anything specifically to hormones in the body. That is why a lot of ladies like to take hormones in addition to noogling for an extra boost to booby growth.