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.