What does “the feet the wrong way round in the toilet cubicle, the teeth brushing” mean?

Solution 1:

I'm not really sure this is an English question, but it looks to me like a reference to bulimia: people who intentionally make themselves throw up ("purge") may use toilets to dispose of the vomit, and brush their teeth afterwards to hide the smell on their breath. There are a number of health problems associated with this practice, so it is considered an eating disorder.

So all of the things in the list are examples of self-harm (as you said, the "sleeves covering the cuts" seems to refer to self-inflicted cuts).

Side note: It is apparently not advisable to brush your teeth in these circumstances. The acid in the vomit means the teeth are more vulnerable to damage from abrasion right after someone throws up. A site I found that has an article by a person recovering from bulimia warns:

Never Brush Your Teeth Right After Purging

Now this is something I actually used to do a lot when I was bulimic! The reason I did it was to mask the smell of vomit on my breath. What I was actually doing without realizing, was stripping some of the protective enamel off my teeth. This enamel is very vulnerable just after purging.

So rather than brushing your teeth, rinse your mouth out with water thoroughly... That will limit the damage done when your teeth are in this sensitive state.

(Bulimia Tooth Decay... 3 Tips on How You Can Protect Your Teeth, by Shaye Boddington)