Did I understand the plot of "Predestination" correctly, or is it really that weird?

Warning, contains spoilers !!!

I just saw Predestination and I really wonder if I got the plot right? Please do not read further if you're planning on seeing the movie!

So, the movie starts with Ethan Hawke talking to John - "The Unmarried Mother". (S)he shares his story about how she used to be a woman (Jane). Some space travel story is thrown into the mix. Basically, as a young woman (raised as an orphan) she meets a man who impregnates her, but leaves her after a one night stand. During birth, the complications result in a sex change. So she becomes John. In the hospital, her baby was stolen.

So far, so good. A bit weird, but I can still follow. But then comes the reveals:

• Time travelling Ethan Hawke was the one who stole Jane's baby! I don't know why.


• The baby was dropped off at an orphanage. So the baby IS actually Jane from the orphanage? How is that even possible? Her baby is herself from the future?


• When Ethan Hawk returns in time with John, John has a one night stand with Jane. So she has sex with herself as a man? Very weird.

To summarize: John and Jane, basically the same person, have sex and produce a baby that is actually Jane. REALLY??

Please tell me I completely misunderstood the plot.