Kylie posted new photos of herself on Instagram Sunday -- the first she's put up since TMZ broke the story that she's preggo with Travis Scott's kid, who he's telling friends is a girl. You can tell she's trying to show off her figure (her belly, specifically) which in these pics looks as good as it always has.

Here's the thing ... we know for a fact she is expecting, regardless of what these photos seem to show or not. In the top photo, she's wearing loose clothes from what looks like her outfit on Friday, so it's hard to get a real good look at the bump here.

But check out her look from Saturday night in Vegas -- she seems a bit more filled out, and is still rockin' loose mom attire ... similar to the day before.

Kylie also posted a pic on Sunday of her with her girlfriends in bath robes, where she looks very thin. Hard to tell when this photo was taken, though ... and angles make a huge difference.