i feel sick about my current situation

Recently, i decided to plan on transferring to a different university, but the schools' calendar weren't aligned. I feel really sick that I have to accept that there's a 90% that I won't get accepted and I have to continue studying at my current university, wherein it has a toxic environment and professors. I am poor so I have to rely on these state universities that offers free education, however I'm not really that smart to be accepted so I have limited options. I feel really sad and it affects my self-esteem not being able to study in a great university wherein I can grow. I fear that I have to force myself to study in my current university.

Because of my financial situation, I decided to apply for work and I got really anxious about the job interview. I overthink about not being able to pass due to my confidence. I was so anxious that my stomach continuously hurt as if the butterflies in my stomach are having a feast there. It made me feel very nauseous and i had to take a few deep breaths to stop these feelings. I am unable to have my interview to day, which means that I should expect more worse thing to happen in the next few days because I might be more anxious than I was today.

Because of these happenings, I got a really low self esteem, in which everytime an opportunity comes to me, I automatically assume that I won't get it or I would probably fail. It's making me feel nauseous just thinking about what can happen in these kind of situations.