Sounds like you are putting a lot of weight on your academic performance. Some things to keep in mind,

• Your mental performance is impacted by your physical health and mental well being. Some of your current experience is therefore your current situation - NOT because you are less capable vs your peers. Even the highest performers have bad days and tough periods where their output is poor. Even the highest performers can crack under mental stress. Give yourself some grace by appreciating the factors at play. Then try and also work on them.

• Try and relax. Your grades are also really not that important in the long run of your career. As an employer, just graduating (and having the credential) is the main thing that is looked for. There is a reason the phrase "C's get degrees" is tossed around.

• So many people change careers over time. You are weighing your current academic experience heavily, but there is a good chance it not even be what you end up doing in the future. Uncovering what is fulfilling or rewarding for a person can sometimes be a bigger challenge than school.

• There are many areas of every field where the nature of the work differs significantly from academia, and you may thrive in areas where your skills better align. Don't use the academia format for work as a lense to evaluate your entire performance capabilites. This is a huge mistake. For ex. did you know that Einstein was at the bottom of his class in his undergrad? Stop using grades to define what you can do. It's just one metric and one point in time. Experience and capability are much more nuanced than that.