You have already made a big statement, you never got baptized. You un-spoke many words right there. Amazing, your parents encouraged higher education for you. You went on to college and accomplished that. Again, you have already made a big point there in itself. Do you know how many ex-JW kids would envy you? Your actions have already made your point to your parents.
Are you in contact with your sister that is 'out' much? I hope you both can have a wholesome, upbuilding relationship with her and somehow have contact with your little sister that still lives at home. Maybe you can help her in some way to open her mind.
I mean that I feel the need to speak out about the truth, which, in this case, is that I have no desire to do anything that might in any way condone or support the existence of a cultish, future-destroying "religion". I feel that by not "speaking up"
You, apparantly, feel a need to speak up to expose the WTS for what it is, cultish, future-destroying . Many here have that need that have moved on but want to help people with their process of leaving. Maybe you could help your sister. Befriend her, sincerely, with just real life things. Maybe you can make little real points, not attacking her religion, but helping her to grow and use her mind. Invite her to visit you and her little niece. Perhaps there is still hope for her.
Reading is important. I hope you have read "Crisis of Conscience" by Ray Franz and his other book as well. A poster above mentioned Steve Hassan's book and he has a few others books on combatting mind-control issues. I belong to an ex-JW group through "Meetup" here in Phoenix and loan out several books for ex-JW members here. Many leave JWs but never read anything to help them identify the real serious problems of the JW mindset and to learn about the 'whole' story.