Is It a Sin to Struggle with My Studies and Feel Overwhelmed?

Assalamu alaikum everyone. I'm in my early twenties, in my final year of college. I chose a major I thought would be safe for getting a job right after graduation, but after struggling through the core courses, I realized I'm not good at it. It was too late to switch to subjects I liked and was better at, based on my electives. Now, in my final semester, I took a beginner Spanish elective and I've loved it so much-I practice a lot and have full marks on all the written quizzes and listening tests so far. But for the speaking test, I messed up really badly. I don't know why, no matter how much I practice, I always do poorly in oral exams. For this one, I knew exactly what to say, but sitting in front of the teacher, I froze, blanked out, and spoke too slowly. After leaving, I spent the whole day realizing all the things I missed. This was one thing I was genuinely good at and enjoyed, but I'm going to lose marks and probably my A grade because I was anxious and my brain just didn't work. But the main reason I think I did poorly on something I was so sure of acing was that I didn't say Bismillah before starting. I pray all five salah and make du'a regularly, but for this, I didn't ask Allah for help and was overconfident. It's like my brain sometimes doesn't function the way it should. I'm also a caregiver for a very sick parent, and I haven't had a full night's sleep in four years. I know that has made me less sharp. But I consider caregiving a sacred duty-it's truly an honor to care for a parent who is vulnerable, and being able to make his life even a little more comfortable brings me great joy. And honestly, that's it. That's the only thing I'm really good at; everything else I do poorly because I feel generally incapable. People say all the pious people and Prophets faced many struggles, and I have tons too, but at least they weren't as incapable as I feel, which makes me feel worse. I don't know where I'm going with this and don't know what I'll do after my caregiving responsibilities ease-I really have no idea. I feel too exhausted to work on developing or exploring other skills. I'm barely studying and just getting by because of the lack of sleep and everything else. I want to do so many things, but I feel like my worth amounts to nothing. I don't know what job I'll get; I don't have any standout skills. I know that after death, only the five pillars and good character matter, and I'm always working on those, but I'm just too tired to do extra. Whenever I'm free, I relax, sleep, or spend time with my dad. Spiritually, I know my purpose, but in this world, I feel absolutely worthless except for being a caregiver, which is all I'm alive for right now, I guess. I always feel forgetful and like my brain isn't efficient with most things. I know how important it is to pray to Allah before anything important, but I get nervous and forget. Is it a sin to feel this way and struggle so much? I know it might sound like a silly question, but right now I need someone to talk to me clearly. I feel so lost, demoralized, and sad-my chest hurts.