Question: Is it possible that I suck at everything, apart from writing exams?
This person had difficulty on various projects after they left school. They do well on exams. Now they are wondering, are they just bad at everything except exams?
Don’t be so hard on yourself. You probably have spent all of your time focusing on grades and not focusing on developing other skills. Work on the other skills.
Think about what went wrong on your projects, ask for the thoughts of others (especially any supervisors and advisers) and go from there.
Keep in mind that people who are just starting to work often have trouble with interpersonal issues. Such things often just take time and experience to resolve.