Is eating her out part of the path where you can fuck her? Or have I screwed up?
Eating out means that you agreed to be her bitch and is a dead end.
There are 3 choices:
First branch: she asks you to be her little plaything.
If you tell her to "send to dick", she gets angry at you, but then she later blows YOU when you see her at the mall.
If you go with the other option, you're stuck eating her out all the time. She never fucks you.
Second branch:
If you chose the "send to dick" option, theres another set of choices once you begin to massage her and she sucks/fucks you. After sucking/fucking for awhile, there's an option for her to be your girlfriend. If you decline, you don't get access to her daughters, but you can booty call her (alternate scenes). Personally, I think the game is more fleshed out if you choose the main routes for all of the characters as you get locked out if you don't pursue the main routues.