these are hypothesis that you're passing off as facts. you need to know:
a) whether the majority of homosexuals are in monogamous same-sex partnerships
b) whether or not they contribute their genetic material for the cause of reproduction (they only need to do it for as often as it takes to get a woman pregant)
there need to be social studies undertaking to prove this is true for the entirety of the world before you can pass it off as common sense. you're talking like someone who doesn't understand the social constructs of sexuality. just because two people of the same sex having sex cannot produce an offspring directly does not suppose all these assumptions of yours, sorry to say.
So you are seriously suggesting that homosexuals might reproduce as frequently as heterosexuals?
That is ridiculous.
Let me ask you this. Do you want a child at some point?