Okay, I'm seriously confused how to get the ass rub scene and how to trigger the toilet scenes and ESPECIALLY how to get straight to sex in bed instead of waiting for her to sleep.
P.S.: Oh, and something about her masturbating infront of you.
Once she has enough trust and sex point stuff (I'd say over 250-300 was when I had them work), buy and give her an Aphrodisiac in the drink menu. She'll likely want to go to the bathroom after and that 'may' work if you barge but if it doesn't I'd reload as doing this will lower her trust and may cause issues with the bathroom.
In terms of her masturbating in front of you, I never could get it to work where it goes any further, but after said aphrodisiac if you take a bath alone, then decide to watch her afterwards she'll be masturbating. I've tried to get her attention during this (cat calling consistently, or watching her and raising alertness and either continuing to watch or jerking it myself when it'd get her attention), but either way she sees you and you "make an excuse" (if someone knows how to do that part, step on up).
As for the sex in bed thing, once she's had an aphrodisiac and I 'think' you'd have to have had done it during the night as well, if you click on her with more than 20 energy at night there may be a new option to do it. Once you've done this once, you can repeat whenever.
Keep in mind that the drug is sold online or at the mall and it's a hefty 20k, meaning it's best to save it until you're sure you can trigger the events.
Like other stuff, the better her stats are the more she'll do with you, and I don't recall if doing it in the bath occurred before or after the drug.