I had been taught that Elokim is a unification of Divine Feminine and Masculine from the root Elo-aH. Is this the case or is the Name Elo-aH also masculine?
No.
ּוַיִּטֹּש אֱלוֹהַּ עָשָׂהו
Devarim 32:15
עשהו is masculine; the feminine version would probably be ּעָשָׂתְהו (or maybe עָשַׂתּוּ like in Rut 4:15, but anyway not עשהו).
There are other examples, like Chavakuk 3:3 and lots of places in Iyov, the first one in 3:4.
Tehillim 139:19 looks feminine at first glance, but in that mizmor David is talking to Hashem directly in the second person, so תקטל is masculine (if You, Hashem, kill the evildoer...).