I would start by going back a year, regular appointments are important even if the actual meeting is relatively trivial as it shows an on-going requirement for treatment or monitoring. Further back than a year then pick what you include based on your current conditions and limitations, for example ; if you had surgery for something that no long impacts on your daily living then I would not include it, but if it does then it may be worth adding. Finally, if you conditions are unlikely to improve or can even worsen then letters and reports that reference this should always be included as they set a marker as you were at a point in time.
Gordon
Nothing on this board constitutes legal advice - always consult a professional about specific problems