Prolactinoma. Usually a macroprolactinoma does not cause weight gain/fat redistribution, just loss of periods, as described. Presumably you are on treatment w/ Cabergoline or bromocriptine. Are the other pituitary hormones ok? Sometimes, a pituitary tumor can damage the other hormones, or secrete something else. Check with your endocrinologist.
Prolactinoma. In women, high blood levels of prolactin usually interfere with ovulation, causing infertility and changing menstruation. In some women, periods may disappear or become irregular, or menstrual flow may change. Women who are not pregnant or nursing may begin producing breast milk. Some women may experience a loss of libido (interest in sex) or painful intercourse from vaginal dryness.