"What I feel bad about is not having published very much in the last few years"

Ben Nicholson's quote reflects a sense of regret and disappointment in his lack of performance in recent times. It suggests that he has not been able to attain the level of success he had hoped for, which he is feeling the effects of this. It is likely that he has been battling to locate the time as well as inspiration to create as well as release his work, as well as this has actually provided aggravation for him. The quote also implies that he knows the relevance of publishing his work, which he is dissatisfied in himself for not having actually done so. This could be due to a lack of confidence in his very own capabilities, or a fear of failing. Whatever the factor, it is clear that Ben Nicholson is really feeling the results of not having actually released a lot recently.