You can also get someone to help write the explanation so it doesn't come out sounding like an excuse but a reflection on what to do different in law school

If it is was undiagnosed till late in your undergrad it is valid. I am currently taking an open semester just to show improvement now that I am aware. You can do the same with citing your LSAT(probably best to get it as high as possible) showing you can do academic related things easily now that you know your specific issues.