I know it does nothing to assure you when you have anxiety to say you have a long time to worry before you get old. the best thing to do is to stay in the present. google mindfulness and try some of those techniques to learn how to stay in the present and it will reduce your anxiety. as for school, I don't know what is available in your area but here there are several options for making up classes quickly online. maybe not as fast as you would like to. maybe your best option would be to take the GED and not worry about making up the credits. take care.