Could my estroven supplements (for menopause) be related to the breast cysts i've had on my last two mammograms?

Yes: Estrogen in any form, including bio-identical or plant-based phytoestrogens, can increase breast density and cysts. It's a good bet that if estroven is helping your hot flashes and menopausal symptoms, it's also interacting with the estrogen receptor. That receptor is present on breast tissue.

Yes, possibly: Excess estrogen can be associated with breast cysts. Have you had your hormone levels checked? Are you on progesterone? You should be on Progesterone with the estrogen, & you might be eligible for Progesterone only as hormone replacement therapy (hrt) which has a protective effect on breast tissue. I recommend bioidentical HRT (bhrt) as transdermal creams as they are safer than other forms.