Kylie was looking for her birth control

But is it true? I'm going to wait until Kris releases the birth video on PornHub.

It's true

Did she announce it herself? So far all I've read is speculation over a baggy t-shirt in a Snapchat photo and people who allegedly know her saying she is. It's always "a source told so and so magazine that.." . Unless she announces it herself or via the show I'm not going to trust any other source.
She doesn't look pregnant. This was 18hrs ago.
http://metro.co.uk/2017/09/24/is-kylie-jenner-shutting-down-the-pregnancy-rumours-with-this-new-instagram-picture-6952786/

Well, if you take a look at how bellies look at 4 months pregnancy
http://infobaby.org/wp-content/uploads/762-4e5632c64b76a09fa7567c34f56dcc64.jpg
You often don't see too much

They all look different. In the end I think it's best to not listen to speculation and to just wait for an official announcement.