Set innodb_buffer_pool_size Parameter in MySql 5.5

I'm running mysql 5.5 on Amazon RDS Instance .(db.m1.large) The variable innodb_buffer_pool_size configure in the parameter group: {DBInstanceClassMemory*3/4} , so the current value of innodb_buffer_pool_size is something like 5.5GB. I run this query :

SELECT CEILING(Total_InnoDB_Bytes*1.6/POWER(1024,3)) RIBPS FROM
(SELECT SUM(data_length+index_length) Total_InnoDB_Bytes
FROM information_schema.tables WHERE engine='InnoDB') A;

and got result of 85GB. What this gap can cause? (5GB instead of 85) , should it necessary to upgrade the instance to bigger one?

Thank you!!