Do your student accounts use the same domain address as educators/admins at your school? If so, I would recommend checking that the admin settings for your account have allowed the app for users under 18. This is a recent change made by Google and has affected a number of users. For more information please refer to the following thread: Sketchup for Schools age restriction issue - #27 by swheat
I can verify that the domain address you provided has been previously registered, so that should not inhibit access.