Another consideration might be that it hasn't been the finest of flying days lately. Now your instructor may think your circuits and landings are just fine, but would you be able to divert to an alternate field, given the current weather? Even if you do nothing wrong, somebody else may screw up and block the runway.
There are a number of boxes that need to be ticked before you can go solo. The majority of those boxes have to do with your own preparation (medical, flying order book, maybe air law) and ability, but some of them are outside your control, unfortunately. Weather is the most important one of those.