I found a picture of a storyboard
.
According to it, Patrick's tentacle which he inserted into Eve is a tongue and it came from his neck.
Of course, the scenario may have been modified in the actual filming.
For example, in the concept art, Eve had oral sex with Patrick in the mating cocoon.
(By the way, I don't understand the meaning of 'The love scene now in the storyboard is rape'. Does it mean 'the concept art is seen as rape' or 'the mating scene on the storyboard that exists apart from the concept art and may have been used for the actual filming is seen as rape'?)
But the basic plot of that scene, Patrick divides his head, bites Eve's arms, and then inserts a tentacle into Eve's mouth, is the same as the above storyboard.
So, I think Patrick's tentacle which he inserted into Eve in the actual filming is also a tongue and she wasn't pregnant at this scene.