From your contents it appears you are eligible for gratuity payment but since you have not opted for GPF and you remained in CPF itself, the eligibility for pensionis at stake.
Retirement Gratuity
This is payable to the retiring Government servant. A minimum of 5 years qualifying service and eligibility to receive service gratuity/pension is essential to get this one time lump sum benefit. Retirement gratuity is calculated @ 1/4th of a months Basic Pay plus Dearness Allowance drawn before retirement for each completed six monthly period of qualifying service. There is no minimum limit for the amount of gratuity. The retirement gratuity payable is 16 times the Basic Pay, subject to a maximum of Rs. 10 lakhs.
CPF rules shall apply to every non-pensionable servant of Government
belonging to any of the Services under the control of the President who-
(a) has been admitted before these rules came into force to the benefits of the
Contributory Provident Fund (India); or
(b) may be admitted by Government to the Fund after these rules come into
force: