I study hard for physics and maths, why do I still not get the grade I wanted?

I'm really bad at subjects like physics and maths, but I'm working hard in physics now. In maths & physics I usually get B's, but in Physics I now get an A, but that's because I work so hard for it. I want A+'s in the subject. I study hard, do practice questions, do every single studying method in existence, go over every topic on the syllabus in detail...so how come I still don't get that A+? :(