what convinced you it wasn't the truth
I always secretly had trouble believing, though I tried and tried. I concealed that even from myself, because I figured something must be wrong with me. I knew there were major flaws in all of their teachings. Major.
I tried so hard to live as a superfine jw, good association and all that. But it was such a sad existence. I hated field service and the lack of joy in life in general. I hated the fact that education was against the rules. I hated the fact that most of my hobbies were seen as ways to distract me from jehoopla (wholesome things like doing artwork and fundraising walks for charities).
The lack of love was horrific. The people I dealt with (few exceptions) had puny consciences and were huge bullies and manipulators.
We started studying that red Revelation book at the Tuesday book study. It was so bizarre and violent. What kind of sick god executes kittens and babies because they weren't in the right religion?
There were lots of end-times calculations in it. I did the calculations on paper and on a calculator and the numbers didn't add up to what was in the book. I even showed several people and none of them could come up with the "right" answer by adding the numbers. Finally they told me the brothers have secret knowledge and I was wrong for doubting. That made no sense!
and that leaving wasn't a
horrible decision that everyone in the truth makes it out to be?
That took time. I ultimately decided being a jw was such a hugely miserable life that I'd rather die. I looked out for lightning bolts for a long time. Gradually, I realized the lightning wouldn't be coming.
My advice is to give yourself time and patience. The truth can withstand all scrutiny. It's ok to think. Jehovah gave you a brain. Thinking is not wrong.