normally you trace the process and fix the SQL and not adding memory blindly

looking your init.ora there are some funny values:

none of your control file is multiplexed? that is basics you know, looking this, have you multiplexed your redo logs?

how big is your database? isnt you SGA so exaggerated? 7GB db cache, 900mb shared pool reserved size (what on earth would need 900mb shared pool chunk...?!), 3gb shared pool, you have TONs of PL/SQL codes and not sharing SQL? 800mb large pool, are you using MTS?

optimizer_index_cost_adj=1.... who told you to set that?

your utl_file_dir is duplicated, you should be using directory anyways