Bromos of teens how tf to deal with this

Advice is welcome if you are currently parenting a teen. Not interested in being shamed by someone who only has babies or small children and even less interested in being told to go all hard ass on an extremely sensitive kid with rejection dysphoria by someone who's kids have long flown the nest.

Do some teens just have an extreme phobia to taking gentle advice from their parents? Every suggestion I give is immediately shot down and nothing ever has a solution and nothing will ever help apparently. I am so over her defeatism and dooming.

Yesterday she was in tears because she was having a hard time getting work turned in online and is risking failing the class and being kicked out of showchoir despite having her work done. I, an idiot, suggested emailing the teacher but of course that's ridiculous, the teacher won't see it, she will get mad that she asked, it's not going to help. And I'm over here like "what do you have to lose?!?!" She's worried about failing but is too afraid to email the fucking teacher?

Today she got some boots from Amazon that she had been waiting on for a long time. She used gift card money she got for Christmas on an account she made. To her dismay the boots were too small. She's very upset. I tell her it's usually easy to return things off Amazon but she has every excuse as to why that won't be the case. I try to explain that I can look at her account and set up the return and take them to the return drop off while she's at school. But she won't stop talking over me saying how none of that isn't going to work. She wants to try to alter her boots instead so they fit which I don't think is anything one can do with shoes. I'm infuriated because she isn't even trying and sure as hell isn't letting me try.

And of course my husband doesn't help because he just blurts over over the both of us that "you can't ever order off Amazon again" which saying that he's never going to let her do x again is the first thing he blurts when he gets frustrated and it never fucking helps it just makes a hard situation 100x worse so she shouts "I'm done" and storms off to her room without eating the dinner I had just had ready right before she tried on her boots.

Why is she so fucking resistant to our help. I tried telling her that I return shit off Amazon all the time it's no big deal. That I can order a bigger size and get faster shipping.

(Editing to add since several people mentioned it. She's already in therapy and has ADHD and being treated for that)