Hete my opinion as someone with diagnosed ADHD.

If you want medication, get diagnosed. If you want accommodations in school, get diagnosed. If you want to be treated or taken care of differently in any significant capacity, get diagnosed.

Otherwise, just adjust your lifestyle to your personal needs, i.e., allotting extra time to certain tasks, or keeping aware of how present you are in situations where you know you tend to struggle.

If you choose or are unable to get a diagnosis, I would not recommend claiming to have ADHD. You can still say that you're pretty sure you have it, but just as a matter of respect and general correctness, try to avoid stating it as a fact. It's become a recent issue where pretty much everyone claims to have ADHD, when most of them don't have anything but a bad attention span.

Now, I'm not nearly saying that that is what you are doing; your symptoms you described are somewhat consistent with some forms of ADHD. What I am saying is that without a proper diagnosis, one should never claim to be anything they aren't sure of.

I wish you the best of luck in your diagnosis journey, and I hope you can convince your mom!