Yes, let's tackle the issues which matter most to you.
Most Bible references to homosexuality are concerned only with male homosexuality, for instance Leviticus 18:22 which is addressed to a man: "Thou shall not lie with mankind, as with womankind: it is abomination."
References to lesbianism, if any are even intended, are more oblique, for instance Romans 1:26: "For this cause God gave them up unto vile affections: for even their women did change the natural use into that which is against nature." (Romans 1:27 goes back to talking about men.) Nevertheless, male homosexuality is universally derided and condemned in the Bible, and Christians have tended to generalise that to cover all LGBT behaviour.
The current scientific consensus on homosexuality is that it is largely hard-wired into the brain six to eight weeks after conception. All embryos start female, but at that point if there's a Y chromosome it causes a burst of testosterone which converts first the body, then the brain, to that of a man. If something interferes, a man might not get the full dose and be left with a partly feminine brain which desires men. Under other circumstances, a woman might get a small dose by mistake and have her brain partly converted, and thus desire women.
Therefore homosexual desire is not a choice. The abundance of homosexual activity in the rest of the animal kingdom demonstrates that it doesn't even require the ability to make a fully reasoned choice. It's instinct.
Homosexual activity, on the other hand, is a choice as much as any sexual activity is. That brings us to the question of whether homosexual activity is a sin to Christians. Even if you ignore the direct condemnation throughout the Bible, all sex outside of marriage is sinful. According to most denominations marriage is by definition between a man and a woman. Thus homosexuals can never marry their desired partners, and any sex they might enjoy is sinful. Their only sinless choice is celibacy, or else reluctant marriages to the opposite sex.
This is the problem right here. Why has God supposedly created people who can never be sexually fulfilled without damning themselves? Why does marriage, the only haven for sinless sex, exclude them?
Some Christians respond to this, and to gay rights campaigns, by attempting to prove that even homosexual desire is a choice by converting gays into straights. This is the impetus behind the whole "ex-gay" movement. The success rate of these programs is abysmal; since all the subjects are doing is suppressing their natural urges, they are tremendously likely to "relapse". Even the instructors, most of them "ex-gays" themselves, are regularly in the news after being caught having gay affairs.
While homosexuality is not the expected norm for a human being, it's hardly unnatural. It's not your choice, it's not your fault and it's not something you can truly change. You and those around you are just going to have to live with it. Fortunately, if you meet the right woman you can live happily thanks to it.