How can i convince my mom?

I wanna enter school preparatory school until august 2012,she wants me to enter february 2012,here's what happened,when i entered secondary school 2th grade i got anxiety problems when going to school,so i leaved school and entered a special school where you make various exams and study in your house,so i graduated secondary school this month,and i told my mom i wanted to enter until august 2012 because i want to feel like a normal person,like nothing of this anxiety happened,imagine this,i entered 2th grade on august 2010,that means normal people who kept going to secondary school graduated 2th grade on june 2011,and now they're going to 3rd grade on august 2011,that means they will graduate 3rd grade on june 2012 and enter preparatory on august 2012,i wanna be like them,a normal person,i don't enter early,that will make me feel weird because i will not feel like all of this didn't happened,so how do i convince her to make me enter until august 2012?,thanks in advance