Draft not saving

I have just tried to write a post on my blog ( https://www.teenrose.wordpress.com ) and I tried to click ‘save draft’ but there’s a pop-up at the top of the screen that says ‘Oops! An error occured while saving the post. < br > That method is not allowed’

My post has 859 words (want to add a bit more), and there’s 4 pictures (I want to add 2 more). Is there a reason why I’m not allowed to save or preview or add new pictures…?