Sorry, it’s a little bit long
I completely understand where you are coming from. I have been diabetic since I was 2 years old (I’m almost 28). My teenage years were probably the hardest. Like you, I put a lot of pressure on myself if I missed a test. Especially since I played sports and wanted to show I can take care of myself. Here’s my suggestion to you, and believe me when I say, this may take some adjusting on the fly:
Technology is great, use it! If you have a cell phone/watch with alarm capability, set yourself alarms throughout the day. If you want, set one for every time your supposed to test (meal times are usually easy to remember tests). For those easily forgettable times with school, friends, extracurriculars, etc. have an alarm on your phone or on a watch.
Make it a game: when I was little, to make me feel better, my parents had our family guess what they thought my sugars would be. As I grew up, I used that to my advantage. I would have friends guess too. One day in HS, I was starving and just started eating lunch. I was so focused on getting food (not low blood sugar, just hungry) that I had forgotten to test before eating. One of my friends was a little behind our group and when she sat down she asked who was closest (thinking she missed me testing and wanted to see who won that day). I stared at her for a second then scrambled to test. Thankfully I wasn’t too far into lunch for my BG to be affected but it was a reminder for me
Time to “preach” for a second. Being that you are 17, I would imagine that you are getting ready for college. By setting alarms for yourself to test (I still do at the age of 28) will show you, your parents, and your doctor(s) that you know what you’re doing and that you’re ready to take that next step. You’ll also be surprised how setting up structure for your diabetes will translate into structuring/organizing other parts of your life (I am way more organized than I used to be thanks to the T1D structure I set up for myself).
I hope this helps and good luck!