You've already pointed out that there are certain things you have doubts about, and that's good. However, he's going to come full bore with JW reasoning on a bunch of things. In the end, baptism is about head knowledge but also the heart. All he is attempting to address is the head knowledge part. Typical of JW's because nobody can make you feel anything. I think that you are so freaking brave and we're all cheering for you. Do what you can with the advice from others. In the end, you aren't ready in your heart and it isn't a matter of gathering facts and answering questions. You just aren't old enough to make the commitment. You aren't ready maturity wise, as far as they need to know. Some people meet the person they would be great with in a marriage when they're young but they just aren't ready for the commitment. I hope that intellectually you can beat this back, but JW's have answers for everything even if the answer is to "wait on Jehovah" or some similar crap. Keep us posted. We've got your back.
Did your parents become JW's later in life? If so, they had a chance to learn and grow as a person before finding "the Truth", they should understand on some level that being your own person helps you to make mature decisions. Your brain isn't even fully formed until you're in your late twenties. Jesus was baptized at 30. You have to be allowed to do things on your own time. After all, if your parents had been visited with "the Truth" earlier on in life they may not have been ready for it, but you don't just get one chance in life. This isn't your one chance to get baptized. You have many years ahead of you. Maybe you can reason with your parents on this note somewhat. If they were visited by JW's earlier in life and weren't ready, then no amount of pushing would make them ready. In fact, it would have pushed them away and made them less likely to listen when they were ready. All you are doing is asking for the same consideration. Forcing you into something because intellectually you know it is "the Truth" (as far as they're concerned) doesn't make you emotionally ready. A young man or woman can have sex much earlier in life than they're ready. Merely having some part of an equation doesn't make you ready.