I think this line
How can we explain this phenomenon using ray diagrams?
is the issue. At first glance it makes it look like you are just asking for someone to make a ray diagram for you rather than asking about physics concepts here.
An easy fix could be something like
From ray diagrams it can easily be concluded that using a real object, we cannot get a real image from a plane mirror. But, if we shine a torch on the mirror we see a real image on the wall. Why does a real image form despite ray diagrams showing they do not form?
This puts the focus on understanding what constitutes a real image, and how they relate to ray diagrams.
It might also help to explain why you think it is a real image (and not just light reflecting off a surface), and maybe even your ray diagrams showing how real images do not form.