If Torah, Shabbat, and Shechinah (the Presence of God) are all feminine, and without them there is no Judaism, why does Judaism appear to be a bastion of masculine patriarchal power?
You raise two issues with this question: first the role of the feminine in Judaism, and second the lack of female power in Judaism. The answer to the second is easier to answer: Judaism, specifically Rabbinic Judaism which is has dominated Judaism since the fall of the Temple to the Romans in 70 CE, is a product of patriarchy, and the boys are loathe to give up their privilege. Thankfully this is changing, and has been for some decades, but even as women come to take their rightful place as rabbis, cantors, scholars, and educators, Judaism itself maintains the top down model of power antithetical to feminist thinking.
Of course this power is illusory. If you don’t like what your rabbi says you can quit your synagogue and join another. Ultimately the power is in the individual, but the illusion of rabbinic power remains, and the fact that clergy have no clothes is not a widely advertised one.
As to the presence of the divine feminine in Judaism I would go so far as to say that the entirety of Jewish spirituality is feminine (though not female). All five levels of consciousness—nefesh, ruach, neshamah, chayyah, and yechidah (body, heart, mind, soul, and spirit is how I understand them), Shechinah (the Presence of God), and even the voice of God (Bat Kol, the Daughter’s Voice) are feminine terms suggesting something distinctly feminine about them that goes beyond Hebrew grammar. Further the Book of Proverbs tells us that creation unfolds through Chochma, Lady Wisdom, who prepares a feast of wisdom foe those who heed the invitation of her female apostles. And this is just the beginning.
My hope is that Judaism not only opens itself to women, but to the Divine Feminine as well.
You can read more about this in my 2005 book, The Divine Feminine: Biblical Wisdom Literature Annotated and Explained and my forthcoming sequel, Embracing the Divine Feminine: Song of Songs Annotated and Explained (both from Skylight Paths publishers).