Breathe in breathe out. Song?

Its not machine head by bush or any male. Its sung by a woman and i believe it came out during the 90s. I thought it was Sia but i couldnt find anything. The song is so beauitful and real slow. I know the meaning of the song is about during heroin so she says "just....breathe" and then theres a breath at the end. I cant find it anywhere. and it makes me so upset.