Oh - the reason you don't talk about Sex is that this is a trigger for her. You + Sex = Negative feelings. So, for now, strike the word from your vocabulary.
Your goal with compliments is make her feel good. NOT to show her you are changing or you're a nice guy. That's why I recommend complimenting other people as well. You need to get into a giving habit. After you consistently give, you will see people start to give back.
