Hi and welcome! I'm really glad you found us!
What has the Watchtower Society to gain by misleading, changing doctrine, etc? Control, Power, and MONEY. Have you any idea how much money they have tied up in real estate and stocks? The numbers would shock you, considering they call themselves "non-profit".
I think you should start at jwfacts.com In my opinion, this is a great resource as it uses the Society's OWN LITERATURE to prove the points discussed. The thing is, you don't need to look at so-called "apostate" material or even outside sources (though you should check into the latter...if it's good enough for the Writing Department at Bethel to do their research from "worldly" sources, it's good enough for everyone else). The Society's own writing is what shows them to be in error. For instance:
~ failed prophecies
~ flip-flops in doctrine
~ lives lost and relationships ruined due to the aforementioned flip-flops (organ transplants are equated to cannibalism, a woman must scream if raped, etc)
Here's the kicker. The JW's like to say that they are the true religion partly because they use "god's name". In reality, the name is in error. It's a bastardization, a botched pronounciation.
Many of their doctrines are not bible-based. Honestly, I hesitate to even give them credit in saying that some of them may be. They employ a method known as "cherry picking" when using the bible or "quote mining" when using secular writings to support their doctrines. There are some wonderful examples of this to be found online. The book "Life How Did it Get Here- By Evolution or Creation?" is FULL of examples of the Watchtower taking what a respected scientist says and picking out the parts that make it look like the quoted individual agrees with Watchtower doctrine, when in fact, this couldn't be further from the truth!
So basically, the doctrine, the organization is founded and run on LIES. Charles Russell (the founder of the Bible Students) was into Pyramidology and the occult and came up with many of his doctrines from employing those means...If he or any of the "founding fathers" (Joseph Rutherford, etc) of the Watchtower were alive today, they'd be disfellowshipped for apostasy!
They like to use the scripture about the "light getting brighter". I'd encourage you to read that entire chapter in order for you to realize that it's not speaking about anything having to do with increasing knowledge in doctrine... In other words, this is a classic "cherry picked" verse. Now, let me give you an example as to why this isn't an accurate verse to use in regard to the Watchtower and it's doctrines.
Let's say you're in a dark room. It's pitch black. However, to your right is a light switch, but it's one of those "dimmer switches". So, you ease the knob slowly, allowing very little light into the room. You notice across the room that there's a chair. On the chair there's some sort of stuffed animal. You can't make out what type, but you know it's a stuffed toy. You turn the knob a little more and see the shadows decrease enough to reveal long floppy ears. Okay, it must me a bunny! You turn it a bit more and see that it has a short snout, the ears are still there, and it IS in fact a bunny. Now, with the next turn of the knob, would it magically turn into an elephant?? No. It would still be a bunny, but the DETAILS would be clearer. Perhaps you'd see it was blue, or you'd see the whiskers and the button eyes...but it would STILL be a bunny. The fact that the light got brighter would not change that. Now, let's apply this to the Watchtower. When a light "gets brighter" in Watchtower understanding, a bunny doesn't remain a bunny. It becomes an elephant. Which we know isn't possible. So the fact that their "bunny" (let's use the example of the "generation" teaching) turned into an elephant...and then back into a bunny...and then back into an elephant...and then, holy crap, now it's a freakin' dinosaur!!...Well, you see that their depiction of the "light getting brighter" can't be accurate. Neither can their answers to questions about things like oral sex or whether a woman has to scream when she's raped in order to not be disfellowshipped be accurate because they keep going back and forth on those things. The light isn't getting brighter, it's flicking on and off like a strobe! I ask you, if they had "Holy Spirit" and were speaking for god through such Holy Spirit, would they be getting things wrong so often and going back and forth? Is the Holy Spirit, and thus god himself, confused and inconstant? Is that the god you serve?
Something to think about.