You are very smart to be reaching out so early for help–it is the best way to be successful in life–to realize there is a problem and seek assistance. Geometry is different in that it is a visual/practical use of math from the numbering/calculating type. It is less a matter of memory than of application of those concepts to solve problems. However, this forum is not for math. Your expert is your teacher–it is their job to teach you the concepts. See him/her after class privately and tell them you are having a lot of difficulty. They have lots of different ways to teach, using tools that may make better sense to different students. I have a feeling a different approach will make you have an epiphany-type moment, and you will suddenly understand what the concepts are saying. When you get to college, there are actual posted “office hours” by teachers who encourage students to come in when they are having difficulties. This is because the focus is (and should be) on learning the concepts of what is being taught, not just passing a test or getting a good grade. It sometimes helps teachers too, to realize where they may not be making things clear enough, especially if many students aren’t doing well. That being said, when you are in high school, it can be seen as weak (by other kids) to not be understanding what “everyone else” seems to understand (this is NOT necessarily true!). Also, some teachers are more receptive to students than others. If your teacher makes fun of students, shames them, or embarrasses them in front of the class, going to them may not be helpful. In that case, you may want to involve your guidance counselor or student dean. And parents, maybe, depending how supportive they are. Believe it or not, they are all supposed to be there for you when things aren’t going well-they want to help.
Another thought I had is: why do you “think” you have ADHD? If you are noticing things that lead you to that conclusion, have you ever told your parents, doctor, or teachers/guidance staff? There are tricks, treatments, and supportive reassurances available to you now (some of our forum ideas are very helpful, as you have obviously seen because you have been prompted to write about this). Also, physical ailments (sick/headaches) can be a host of things, especially around the anxieties of being successful in school, friends, future career planning, etc, for anyone at your age. Feeling “different” and alone is practically a rite of passage for high school. (And personally, sophomore year was by far the HARDEST year I have had in my life!) Headaches and “sick” sounds more like anxiety. Thinking you might have a diagnosis that is working against you will only make it worse. Ask for an evaluation and tell someone what is going on. You will feel less alone.
Again, taking the courage to open up about this to us is a great thing, and I hope you get lots of good ideas. High school will seem like forever, but hang in there, it gets better and there is a whole world out there that will accept you if you build and develop the tools to function to the best of your ability. Good luck and keep checking in with us!