My DS was feeding once a day (in the early hours of the morning) for a long time before I weaned him at 33 mnths. I do think it's a case of busy boy and you may find if he goes through a developmental leap or as he is getting sick that he may feed more often and then cut back.

At about this age I did the don't offer, don't refuse 'thing' and I think if you are following thier lead there isn't much else you can do. well done on following your instincts