Sorry, I got sidetracked on something more important. This isn't a backup size issue, this is a maintenance plan question about why the transaction log file is the same size or bigger than the DB when no transactions have been made since the time the nightly backup was made and when the transaction...

What is the size of database and its growth? Do you have any issues for disk free space? If you are worried for the database sizes then you could take differential backup route by keeping the size and make sure to perform full backup every 1 week. Make a note whatever action you perform on the database...