Teen diagnosis

Hi the school has referred my son for a ASD assessment he's 13. Not managed going up to secondary. Gets into trouble for talking back, not listening/concentrating or getting upset at timetable changes. At home he has a set morning routine. We walk on eggshells not to upset it. I manage him ok but school seem to set him off. He has friends and loves football but gets angry if his team lose. He's very literal doesn't appear to have empathy for anything. Hates noise and lights, labels. Hes always been a "difficult" child. Has anyone else had a teen diagnosis. Why have we not noticed things before? He's dyslexic and has fine motor issues. I know this is a long road. I just feel a bit lost with it and how to help him.