Firstly, I want to let you know that there is nothing wrong with you having to pace around while you study. There is no rule stating that you must be seated quietedly in order to study - if what you’re doing works for you, that’s great! I may be able to offer a theory as to why you do this that is separate from ADHD, and that is pacing helps to reduce distractions while your brain is trying to focus on your study material. On top of this, incorporating movement (e.g. walking, standing, pacing) with studying can be beneficial in ways like boosting memory, thinking, and executive functioning - so I’d say you’re on the right track
Next, I want to emphasize that just because you pace around, or if you have certain symptoms of ADHD you find online, it does not necessarily mean you have it. The only way to be certain of this is to get a formal evaluation by a psychologist or psychiatrist. Here is an article breaking down the symptoms of ADHD and where you can go to be evaluated for it: [The Ultimate Guide To Identifying and Treating ADHD in Singapore]
Additonally, you could also reach out to your family doctor or a school counsellor to get a referral or advice on the next step.
Finally, I would like to let you know that if you do have ADHD, it is nothing to be ashamed of nor does it mean that there is something wrong with you! Everyone operates differently and getting a diagnosis just means having to adjust your lifestyle to what suits you. Whether that is changes in habits or taking medication, relevant help can be provided and we are always here to support you in your journey (ADHD or not )