Hi there, as you can probably see if you're still lurking, these forums are quite inactive. I'll keep my answer short since I doubt you're still around...
If you feel drawn to a relationship with God, and that's what makes you happy, go for it.
With regards to the Bible, yes, the OT is full of horrible stuff, and frankly, I never have been able to get past it. People just write it off as "That was before grace," or something similar, but if God never changes, and God is love, and God could approve some of these things depicted in scripture, we have a problem. Of course, some progressive Christians say those stories are just that--stories, which depict the values and mores of a given culture in a particular time.
I wish I could help you on that one, but I'm no longer Christian. There are scholars/pastors out there who may be able to help you.
As far as changing the attitudes of loved ones, just give it up. I have a sister who never has accepted by sexuality, and I'm your age. I came out to her well over 10 years ago. If she won't listen to reason, then maybe just distance yourself from her a bit, because who wants company that pulls you down?
Regarding your partner and anal sex, I can't help you there, either. Talk to him about it. As far as what God wants you to do sexually, I'd say as long as you're not harming your partner, I don't think God cares a whole lot. Hope this helps... some.
"And though I may not know the answers, I can finally say I am free. And if the questions led me here, then I am who I was born to be." --Susan Boyle
"If all fools could fly, the sun would be eclipsed forever." --Dutch proverb