Spelling in X certificate and XII certificate are different.

I have my name as A. Fathimaa (double "aa" ) in my X SSLC certificate. Where as, in my XII certificate it is A. Fathima (Single "a)". I carried on with my XII Certificate spelling until i completed my PhD. My voters id, driving license, aadhar card, bank passbook & everything is with the same spelling (ie, as per in XII certificate) . I completed my X in 1998 and XII in 2000. Its 15 years since now. I'm a spinster. BUT I DN'T HAVE A PASSPORT YET. Now i wanted to Change my ENTIRE name due to Numerology, My parents insists. Nothing could be done about it. So i'm gonna apply it in gazette. The gazette application form has a column as Old name with proof, either birth certificate or school TC. I was born on 1982 n i dn't nave a birth certificate. During my studies the TC will be given in school office, so there is no TC too. My questions are, 1. With which spelling, i have to apply in gazette? With 10th or 12th? 2. While applying for passport, how to prove myself that, the person in 10th and 12th are one and the same person? [Note: Some say that, I can change my name by going to the school where i did my 12th and get it changed in the Certificate itself. Correction vl be done and a seal vl be stamped on it. I cudn't take it. Is it true? Is it not forgery? How one could change one's name in an Original certificate? By heavens, if it is the correct procedure, all my Original certificates are laminated. Hw it vl be done?] I cudn't find anybody to give the correct information. I'm so confused. Plz do help me. Thank you all, in advance.