Feeling lost and questioning my worth

Assalamualaikum everyone. I hope you're all doing well insha'Allah. I need to get this off my chest because I feel like I'm reaching my limit. I started working when I was 19 because my father helped me get a position. I'm 23 now. During the pandemic, I was doing my A-levels and my predicted grades turned out really poor. To be honest, even if I had taken the actual exams, I don't think I would have done much better. After that, my dad suggested I work with him at his company. He's a wonderful father who only wants what's best for me. At work, I don't have much to do most days - just some emails here and there. Meanwhile, I've also been continuing my studies. I enrolled in a two-year diploma program and alhamdulillah, I've already passed 5 subjects with just 2 left. During this time, I considered moving abroad to pursue my bachelor's degree, but I needed certain grades in Physics and Chemistry. So I began studying Physics while working and continuing my diploma. Today was my practical exam and I performed terribly. I genuinely feel worthless and like I haven't accomplished anything on my own. Everything I have seems to be because of my father's help and Allah's blessings - I feel like I haven't contributed anything myself. It's not that I believe I can't succeed. I really want to achieve something in life, like others around me seem to be doing. I want to make my parents proud just like other children do for their parents. Honestly, I'm not even thinking about marriage because I feel like I would mess that up too. I don't know what direction to take in life anymore. I've had some dark thoughts, but I could never hurt my mother like that, and my faith as a Muslim prevents me from considering such things. I'm just so tired of myself and don't know what to do next.