Even if you aren't using a set curriculum, I'd suggest that you start taking more detailed personal records for your own protection.

I'm guessing that you probably take basic notes while you're flying regarding student performance, so that when you land you can conduct a proper debrief, right? Why not consolidate that info onto one plain piece of paper? There's no reason that you need to write down everything in your own logbook if you keep the notes from the lesson. (I put mine into a 3 ring binder).

The FAR's set out what you must keep as an absolute minimum. For your own protection, I suggest that you keep much more detail, and keep it away from your logbook. Remember- in the future, your student's logbooks won't necessarily be available for you to cross reference (they might be destroyed in a post impact fire or something?). And your student might not be willing to cooperate with you (particularly if they or their family are suing you for negligence after an accident and claiming that you didn't provide adequate training).