I've been wondering this for years, more so within the past couple of weeks. The reason that my analyzing it has escalated is that I have my first hrt appointment next week and I want to be sure that I'm not making the worst decision ever. Unfortunately, the more you analyze something, the less clear it becomes. I've been kind of looking at what's true and what's not and trying to decide if I need to keep that appointment. This isn't really something where I can say I'll just give it a shot and if it doesn't look good, I'll stop with no ill consequences.
Left to my own devices, I am without a doubt a woman. If there was no threat of "you can't do that" from society, I would do it in a heartbeat. I think that's the real clincher here and really what I should be focused on, but for some reason those other opinions still count for me. My personality is totally different between being in girl mode vs male mode. As a woman, I feel better about myself and have vastly more confidence. I also actually care about the way I look and my health. As a man, I try to keep a low profile so I don't appear threatening, I couldn't care less what I look like, and insist on habits that slowly kill me with no real desire to prolong my life.
So based on my own experiences, no you can't be talking yourself into being trans. But you can be talking yourself into not being trans, at least temporarily.