CS,
Yeah, it is super confusing. You correctly point out that the scripture refers to them as 1) Jews with 12,000 out of each tribe (but they don't correspond exactly with the tribes of Israel), and 2) male virgins.
To me, the insane part of the teaching is that the part about them being Jews (spiritual Israel in JW speak) and male virgins are symbolic but the 144,000 is literal. Either its all symbolic or all literal. It makes no sense to pick and choose but that's what JWs do on virtually every aspect of their unique teachings.