I am the parent of someone with adhd and Aspergers
The actual diagnosis is a complicated procedure that can take some time. You should go to your gp and discuss it and ask for a referral to a specialist. There are quite a few stages to go through, including with psychologists. You should take an Internet diagnosis with a pinch of salt.
I appreciate you don’t want to discuss it with your parents but their input can be very helpful to the process, likewise that of school. They are asked to do some form filling to help diagnose.
Your own observations are not necessarily enough.
If your behaviour had been of concern to schools over the years then if they suspected an issue it’s most likely they would have started the process themselves
This is why you can’t self diagnose. You may be looking for symptoms to fit the diagnosis. It could be adhd, it could be something else or it could just be your personality.
You need to speak to a professional so make yourself an appointment