Picking the right innodb_buffer_pool_size

Don't forget that InnoDB Buffer Pool Houses Data and Indexes

Please run this query

SELECT CONCAT(ROUND(KBS/POWER(1024, 
IF(PowerOf1024<0,0,IF(PowerOf1024>3,0,PowerOf1024)))+0.49999), 
SUBSTR(' KMG',IF(PowerOf1024<0,0, 
IF(PowerOf1024>3,0,PowerOf1024))+1,1)) recommended_innodb_buffer_pool_size 
FROM (SELECT SUM(data_length+index_length) KBS FROM information_schema.tables 
WHERE engine='InnoDB') A, 
(SELECT 3 PowerOf1024) B;

This will tell you how big the InnoDB Buffer Pool Needs to Be. Since you only have 24GB of installed RAM, then innodb_buffer_pool_size needs to be 18G (75% of installed RAM) or the query's suggestion, whichever is smaller.

Would it be a good idea to increase my innodb_buffer_pool_size so that the index space would fit as well?

Yes, it would.

If your data size is 11.5GB and your indexes are over 11GB you might have too much data indexed, or improperly indexed, and may want to get someone to look at that.