I do not think it is laziness. You sound conscientious in you r usual willingness to stay later. You are not bad. Remember you were contracted to fulfil a role and you already do more than that. The true responsibilty for this situation is not yours. Upper levels delegate responsibility downwards including the decision. it is important that you look lokng and hard at your actual role and what you are willing to give. maybe you could ask for extra hours as paid if possible, or extra time if you have a flexitime agreement?I have been in and out of office environments for over 20 years. stress is at an all time high. there are many reasons for thism but you are the important one here. No prizes for heading for a breakdown!!