First of all, thank you for sharing this. It takes courage to talk about what is going on inside your mind.
What you are describing is not weakness and not imagination. This is how anxiety and overthinking disorders actually work. It usually starts with one fear (exam, future, job, failure) and slowly the mind learns a habit of constantly thinking “what if something goes wrong”. Over time, this becomes automatic and exhausting.
You are not broken. Your brain is stuck in threat mode. That is why thoughts keep coming again and again even when you logically know they may not happen.
Also, reading symptoms online and relating to them does not mean you are “making things up”. It means you are trying to understand your pain. Anxiety and OCD often come together, and both are very treatable conditions.
Next Steps
The most important next step is this: please consult a mental health professional in real life (psychologist or psychiatrist). Since this has been going on for 4 years, you should not fight this alone anymore.
Anxiety and OCD respond very well to therapy and sometimes medicine. This is not a lifetime problem if treated properly.
Also, please stop trying to solve everything only inside your head. Your mind is tired. You deserve support.
Health Tips
When thoughts come like “What if I fail?”, “What if I don’t get a job?”, don’t try to fight them or prove them wrong. Just say inside your head: “This is my anxiety talking, not reality.”
Do not Google symptoms again and again. It increases fear and makes OCD and anxiety stronger.
When your mind is racing, bring your attention to your body. Slow breathing, walking, washing face with cold water, or holding something cold in your hand helps calm the nervous system.
Limit overthinking time. If your brain starts worrying, tell yourself: “I will think about this later.” Then gently shift to something physical like walking, bathing, or cleaning.
Most important: your future is not decided by your thoughts. Anxious thoughts feel real, but they are not predictions.