The 18-year-old was in disbelief after it was revealed she had secured a netball contract in the same year as being selected for the White Ferns.
``It's been quite a crazy year, but pretty cool to be able to do both. At times I can't really believe it,'' Heffernan said.
Heffernan replaces Dani Gray, who suffered a serious knee injury during the Southern Steel's round four match against the Pulse in May.
An MRI scan revealed Gray ruptured her ACL and damaged her MCL and meniscus. Cartilage damage was also discovered.
Despite there being a spot in the team available, Heffernan was surprised by her call-up.
``I knew there was a possibility when Dani unfortunately got injured, but I was still surprised,'' she said.
Heffernan will need to make the transition from her usual position of wing attack to slot in to Gray's vacant wing defence role.
She did that in the second half of the Steel's win over the Tactix and impressed when landing five deflections.
``I knew when I got the chance I would have to play well, so it sort of felt like a bit of a trial,'' Heffernan said.
She should slot seamlessly into her permanent role in the Steel, given she has been training with the team since the pre-season in January.
The Steel travels to Auckland today to prepare for tomorrow night's game against the Mystics.
The Northern Stars claimed their first win of the 2018 ANZ Premiership season last night, beating the Mainland Tactix 56-53, NZME reported.
After suffering a discouraging 12-game losing streak which dated back to last season's ninth round, the Stars were victorious at Papakura's Pulman Arena.
