When i thought we were finally chill gang

my mum's super dooper trooper mad at me that i didn't tell her my exam results straight away in that exact moment (i waited 1 and a half days to tell her she's acting like it's the end of the world) and she's upset cause she's "Always supported me through everything" and she thinks i'm using her reaction from when i got my first math extension exam back as the excuse for why i didn't tell her (i mean yea but also cause like wtf bro you're scaring the shit outta me)- and she's also mad that i'm not using my brother as a tutor- which i did ask him for help but i didn't have the whole- designate an hour a week for him- so she's gonna use that as the reason why i'm not getting A's.
I honestly do and don't understand why she'd be upset- but not mad.
Like ok ur daughter didn't wanna tell u her marks cause she's concerned for your reaction and because she's not used to getting just passes- and sure you think she doesn't trust you- but just perchance would you consider why instead of not even allowing me to speak because you don't wanna hear my 'excuses'? nope.
Anyways now i gotta deal with my dad. And i thought it was settled...
I don't get why she's so mad gang- am i in the wrong?