determine redo log size, number of redo log files
The recommendation is to have log switches occur a few times an hour. If you have a 100 log switches an hour with 50MB redo logs, you need e.g 1GB redo logs for 5 log switches/hour.
100*50 MB redo/hour for a 6.5GB database is unusually much though.

You can add the new logs, e.g:

ALTER DATABASE ADD LOGFILE THREAD 1 SIZE 1G;
ALTER DATABASE ADD LOGFILE THREAD 1 SIZE 1G;
ALTER DATABASE ADD LOGFILE THREAD 2 SIZE 1G;
ALTER DATABASE ADD LOGFILE THREAD 2 SIZE 1G;


Then force log switches until the new logs are used (CURRENT status) and old logs become ACTIVE/INACTIVE by:

ALTER SYSTEM SWITCH LOGFILE;


Then drop the old logs:

ALTER DATABASE DROP LOGFILE GROUP 1;
ALTER DATABASE DROP LOGFILE GROUP 2;
ALTER DATABASE DROP LOGFILE GROUP 3;
ALTER DATABASE DROP LOGFILE GROUP 4;


If you can't drop a logfile group because it is ACTIVE, do

ALTER SYSTEM CHECKPOINT;


so it becomes INACTIVE and try again.