Here's a mod I made, it can guide you through the game. Just rewind everytime you see a blue warning, then you're guaranteed to see all lewd scenes. ...Or you can tell me where exactly the locked scenes are in your gallery and I can give you more info about them.
Glad to help! Though I have to say, your problem is really unusual. 11/30 scenes missed while following the walkthrough? How does that even happen? Are you sure you haven't seen these scenes already and the game just doesn't register them as unlocked? I'm just trying to save you from a fruitless third playthrough.
There are Accumulative Guides that come with the PC version of my mod. Open the A one, go through the red rows in the table and see if you remember watching them. The table lists all the lewd scenes, if you've seen them all, there aren't any more.