[Allison presses down, so Derek presses up with his hips. And just to make sure she can feel the bulge growing beneath her, his hands find her hips, pulling her down to his lap.]
Other options:
Sorry about the delay. Holidays. :)
[Allison presses down, so Derek presses up with his hips. And just to make sure she can feel the bulge growing beneath her, his hands find her hips, pulling her down to his lap.]