Aaah that's a classic one. You didn't mention what walkthrough you're using to get the "right choices" but I'm assuming it's either a) Fuwa's one, that doesn't specify what "yes" you should pick (and it does matter), or b) chem is amani's one that according to some friends of mine doesn't work with everyone.
I was sent these sequences long ago by a friend that suffered in trial and error in this part and it worked for both her and me. See if it works for you too. It uses up and down instead of the choices themselves to be less spoilerish and because some choices are "the same". The sequence starts with the answer to the "Do you want to feel even better?" choice:
Down, down, down, down, down, down, down, down, up, up, up, up, up, up --> Good Ending
Down, down, down, down, down, down, down, down, up, up, down, up, up --> Bad Ending