Hi blink! And a very big welcome to you!
Your dad sounds so much like my ex-husband. Very controlling and unable to fathom how anyone could have any questions or doubts about the Watchtower's teachings. Literally unable to grasp why others might see things differently. Pathetic. But, he was raised in an authoritarian household himself, not allowed to question things, and then the cult control of the Watchtower on top of that background, well....
What I've read is that "control freaks" are full of fear, motivated by fear. The conflict here is that JW's believe the Bible is truly God's Word, and the Bible teaches at John 4:18 that "there is no fear in love, but perfect love throws fear outside, because fear exercises a restraint."
People like your dad and my ex-husband (father of my children) feel that they must control others for their own good. They have no confidence in other people or any real faith in God to take care of matters. My son had a very hard time with his dad at your age, and under very similar circumstances. While I had a great relationship with my son, he practically hated his father. His father could not imagine that there was ANYTHING about himself that could possibly cause anyone not to like or trust him, so he too believed that I tried to poison the kids' minds, tried to turn them against him. But I never did any such thing! I knew that kind of thing is cruel to the children and is harmful to them and does no good.
People like that cannot believe that young people can see things for themselves, and will ultimately work things out for themselves. But they do, and you will too.
You might enjoy reading all the characteristics of cults that the WT Society matches up with, at Cults 101.
All the best to you!