Reflection is an exploration and an explanation of events–not just a description of them.
Genuinely reflective writing often involves 'revealing' anxieties, errors and weaknesses, as well as strengths and successes. This is fine (in fact it's often essential!), as long as you show some understanding of possible causes, and explain how you plan to improve.
It is normally necessary to select just the most significant parts of the event or idea on which you're reflecting. ... If you try to 'tell the whole story' you're likely to use up your words on description rather than interpretation.
It is often useful to 'reflect forward' to the future as well as 'reflecting back' on the past.
(Martin Hampton, Department for Curriculum and Quality Enhancement, University of Portsmouth)
http://www.port.ac.uk/media/contacts-and-departments/student-support-services/ask/downloads/Reflective-writing---a-basic-introduction.pdf