You seem to view married couples who contracept and sodomite couples as existing on an equal plane. Sodomite relationships are unnatural not only on the physical plane but also on the spiritual and emotional planes. Eschewing the physical act does not negate the other issues.
It wasn't until the mid-19th century that the word and concept of "homosexual" was even invented, in the taxonomy of pathologies then favored by the psychiatrists. Before then, the only relevant categories were "lust" and "sodomy", neither of which required a particular "class" of people to engage in them.
Sodomy and contracepted intercourse are both unnatural acts, both perverted (turned away from the true nature and purposes of sex as created by God), and both mortal sins. They are morally congruent but not, of course, identical.
Every mortal sin is, in some ways, like every other mortal sin; like some other mortal sins; and like no other mortal sin.
Married couples who contracept are guilty of the additional sin of sacrilege against the Sacrament of Matrimony.