Hi Faboo,
You sound like a great and conscientious young woman. I agree with your thoughts. Unfortunately, your parents most definitely are trying to take advantage of your vulnerability to get their way. They think that they're doing the right thing because they really believe in the religious tenets of Mormonism. Unfortunately, what they're really doing is sending the message that their love for you is conditional. Living life for other people is a tradeoff: it exchanges some quantity of freedom for some quantity of security. Only you can decide what the right balance is. It's not all-or-nothing. What makes this difficult is that they're your parents.
The Church deifies heterosexual marriage. It's at the heart of the Mormon system.
You're lesbian.
Mormonism + Homosexuality = Disaster
No matter what you do, you're going to hurt your parents. But please remember that it's not your fault. You're perfectly fine just the way that you are. Some people are born Caucasian, others Asian, others Black. Almost all are born straight. Some are born gay. This is just human variation at work. It's enculturation that's the problem in this case--or to put it less charitably, Mormon brainwashing.
If you believe, as most of us here to, that Mormonism is false, then your parents are the victims of an institution peddling immortality in Disneyland in exchange for praying, paying, and obeying, most especially when it comes to marrying an opposite sex partner. That's not an option that's realistically open to you, so that's a show stopper. But even if it were, since you know that Mormonism is false, what's at stake here, really, is your parents' feelings and the risk of their rejecting and shunning you.
Rejecting and shunning you...because you were born lesbian. And that's a flat-out contradiction to the entire Mormon belief system. The reason that homosexuals are such a threat to the Church is because if they Church were to accept that sexual orientation is fixed by the time of birth and that at least 1 in 50 individuals is homosexual, they would have to acknowledge that their own dogma is false, which, of course, they would never do. Therefore, they'll mercilessly try to pound a square peg into a round hole--a futile, but destructive, exercise.
My gay (ex-)Mormon friend, Doug Stewart, committed suicide:
http://www.affirmation.org/suicides/douglas_stewart.shtml. All he wanted in life was to find lasting love. He couldn't, and he gave up. I don't want that to happen to anyone else. Your sexual orientation and lack of belief in the Church is a MUCH smaller threat to your parents' well-being than the imposition of their belief system on your life would be to you. It would make you miserable, and remove whatever prospects you had for happiness. It would be a complete disaster. It won't work.
It's not your fault that you're lesbian, and there's nothing wrong with being lesbian, despite what society thinks. It's not your fault that you were born to Mormon parents. Had you been born to atheist professors at Berkeley, you'd be set. In a way, you just got unlucky because there's an "impedance mismatch" between your biological hardware and your parents' cultural software.
Under the circumstances, I think that the easiest way forward would be for you to get away from your parents--far away--and live your life. You'll be less of a threat to their beliefs that way, and they'll have very little power over you. This is hard, but you're already hurting, and you deserve so much better, Faboo, and I'm confident that you're going to find it. It'll take time and effort, but you're going to be all right.
I understand what it's like to live one's life for others. Again, it's a tradeoff of freedom for security. But what are the hidden costs? No girlfriend (or the necessity for a furtive relationship). Constantly disappointing your parents. Remaining in a state of misery and blaming yourself. These are all harmful. No matter what you do--including nothing at all--there will be suffering. That's what makes being human so miserable. We can't avoid some amount of suffering, oftentimes a great deal of it.
If I can give you one guiding principle that may be helpful, it's this: Act so as to expand your freedom over the long term.
One example is school. Getting a doctorate would take a long time, but it would move you up the social hierarchy and confer on you a serious degree of credibility. As I tell friends, "Stay in school...forever." Another example is money. Save money. Plan for the long haul. Maximize your 401(k) contribution, to the legal limit, each and every year.
The general idea is that just like money compounds with interest (or stock investment returns, etc.), if you make little, positive changes today, in 30, and 40, years, you'll have an enormous amount of money, or knowledge, or relationships. The goal should be to make little changes that favor your happiness, and then keep them going so that they're silently "compounding" for you to expand your freedom in every way.
As difficult as it is to understand this if you come from a Mormon background, people pleasing harms you. It's good to be selfish. I think that you could use a good dose of selfishness. You might want to read Ayn Rand's _The Fountainhead_ or her other books. She wrote an essay on "The Virtue of Selfishness." Put yourself first, because while no man--or woman--is an island, everyone wants to hang around a winner, and to become a winner, to become excellent, takes a great deal of practice and individual determination.
Believe in yourself and act so as to expand your freedom over the long term. The rest will take care of itself.
Also, the current situation that you have with your parents won't last forever. Tug-of-war games are only possible if there are two sides. If one side won't play, there's no game. To pick up the rope in the Mormonism game would put you at an immediate disadvantage. Don't. The situation with your parents will exist so long as you give them power over you. Take back your freedom--one bit at a time. Go at your own pace.
Don't forget about YOUR own importance. You're not some piece of scenery to decorate your parents' lives. You're an adult and your own life matters, but it can only matter to you if you claim it.
If your life isn't about you, then whom is it about?
In my view, the only possible answer to that question could be, "The love of my life." And if that girl isn't in your life, then I promise you that as loving as your parents may be, they'd only be a pale substitute for the real thing. Life is for living meaningfully. Take back your life and live it on your terms by experimenting and making little changes that move you closer to your dreams, day by day. Know that the going will be very rough at times, but one day, no matter what you do, you'll be 40. Imagine that right now, looking back at yourself today, right now. What does the 40 year old want to say to you today? Can you imagine the 40 year old happy?
I can, arm in arm with her beautiful wife.
Sending You Encouragement,
Steve