So this girl claims to be 6 months pregnant.
Here is the article:
hxxp://www.news.com.au/lifestyle/parenting/pregnancy/teen-slams-strangers-who-accuse-her-of-faking-her-pregnancy-because-her-sixmonth-baby-bump-is-too-small/news-story/f36c53cc5aec604d3af8b7570e1c6707

More like 6 minutes pregnant to me...

I have seen extremely fit women whose ab muscles basically kept their belly from popping, so they might look 16 weeks at 40 weeks, but...

The article says she's supposed to be 20 weeks in that photo. Dunno, man. The only way she could prove it is by sucking in and revealing that her uterus is full -- there's really no way to fake that one. Without seeing her do that, I.. guess it's possible she's pregnant? It'd be one hell of a small pregnancy, though.

Is she pregnant with air

Could be legit. Some women carry small, especially if the are tall and 6 months is about 24 weeks. That's just over half way through the pregnancy.

She is still hella cute though, tiny belly and all!

It's certainly plausible.

She looks quite tall, maybe that's why. I remember a TV series where women suddenly start giving birth without prior knowledge or any symptoms of being pregnant. A quick resolution is a blood test. Can't fake that.

There was that "I didn't know I was pregnant" show from about 10 years ago that showcased twig girls and ones with flat stomachs giving birth to full term babies. Also not every pregnancy results in a huge belly (or anything bigger than a beergut). But only a pregnancy test will conclude anything.

This is possible and I have seen this one a girl I once knew, she only got a tiny bit big at the end and had a baby only a bit over 5 pounds.

... but this article seems suspicious.
Here social media accounts all started after this article was published by the Sun a few days ago.