Like Skallagrim said, you have to be clear with your posts 'It left her open to his shove from his other arm, Shenestra had no choice but to fall back. The whine of turbines were suddenly heard just as Shenestra fell onto her back.'

1. You never said the hand made contact,
2. You said Shenestra had no choice but to fall back, which can easily mean, falling backwards.