Have a 504 plan because it will help you to navigate through the loads of make up work from missed days, along with with things like extended time on tests, and easy access to the nurse's office when needed. Not all teachers are going to understand your situation and a lot of them will be less than helpful. You also aren't in elementary or middle school anymore. You need to be able to take charge yourself and not have your mom do everything for you. Showing teachers that you are responsible and willing to work with them will make them more open to working with you. Tell the school what you feel like you need because the school officials won't always think about specifics. These accommodations are only there to help you and not hurt you.
Do not separate yourself from events and other students at school. Just because you have a chronic illness does not mean you shouldn't participate in prom, Friday night football games, pep rallies, spirit week, or join in any club. Despite the circumstances you don't want to deprive yourself from the normal activities of high school. You have just as much right to be apart of school functions as everyone else. Even if you are drowning in make up work make sure you go out and have a little fun.
Get some rest! Most chronic illness patients struggle with fatigue. Take the time to care for your body and treat yourself to a nap every once in a while. Spending 7 hours at school is quite draining especially when you have to walk around the building over and over again just to get from class to class. Grades is important however so is your health. If your body doesn't get enough sleep and you aren't functioning properly you won't be able to focus and keep up in class.
Keep as caught up with your classes as possible. Once you miss a day in class it is very hard to keep up the pace just like the other students. When you are there make sure you are doing the work put in front of you and not slacking off. This will help to save you from a large amount of stress. It will also allow you to spend more time doing fun things versus sitting inside trying to get caught back up on algebra homework.
High school is complicated already and adding in a chronic illness can make things even harder on students. With these helpful strategies my high school experience has been made a little easier. Three weeks ago I started my senior year and I'm very excited although very nervous because I know the amount of added stress is not what I need but I plan to be as productive as possible to make my high school career successful!