Hello

Don't be so anxious about your preparation. Just be calm and try to make time table and start from zero again. You are not late. Your overthinking not only affects your health but it also make your time waste. So don't overthink just start in a beast mode. As your class 12th boards are coming so analyse the syllabus first. Then mark the most important chapters and do that. Make your foundation strong. For boards , NCERT is the main so complete it first. Then revise your syllabus weekly so you do not forget the formulas. Give PYQs it will let you know about questions coming in exam.

I hope this helps you!

All the best !