However, with one more chance this coming weekend to clear the 4.70 metres required before the June 22 nomination cut-off, McCartney is not giving up all hope.
"These competitions are tough and they're going to be a tough thing for my system to be able to handle; but when there's nothing left to lose and you've only got one week left before qualification ends it's worth it.
"You just don't know what's going to happen... there's a couple of interventions that we're thinking might be able to achieve something, so there is a little bit of hope in that."
McCartney says it's been a difficult past two years battling her ongoing health issues and competing in these latest qualifying events has shone a light on just how far she's fallen off the pace of the world's best.
"Unfortunately, leading into these competitions, I was clearly not in the best condition to be giving it a go.
"It is a tough pill to swallow but I've been going through this for quite a long time now so I'm a little bit more attuned to it.
"When I think back on the last couple of years, it seems like it goes so quickly but I just haven't been competing and it's a really, really long time to not be vaulting and competing and that takes a toll."
While McCartney is determined to do her best to pull a qualifying vault out of the bag this coming weekend, she says that just the fact she is competing again is a welcome step on the road to long-term success.
"It is also part of the long-term game here; learning to deal with this, learning what I need and how to get around it and just doing some competitions again."