anxious about school

Going back to school in a week and I have to start a new class since I got held back a year (I got really sick)… I keep telling my friends how nervous I am, but they say I’ll be fine and it will all work out… drives me a bit insane since I feel like I’m just worrying too much, I just want to feel like my feelings are valid ig? Last time I started a new class it went really horribly and I can’t help but fear it will happen again （ ;  ; ）