Sorry.. I keep thinking in the Time Capsule discussion area we are talking about TC..
If you copied the pictures to the WD drive then none of this would have happened.. it is the fact you deleted them from the Mac and assumed you would then have a backup inside the TM.
I know it is well after the event but Pondini in that same FAQ states with extreme clarity
20. Once my Mac is backed-up, can I delete some stuff to save space?
NO, NO, NO! That's a terrible idea !
See Q20. for the rest of why not.. the disk is slowly filled with current changes to file.. If you manipulate a large file it is backed up every hour.. it takes very little time to fill up the disk.. especially if it is so small.
Once full TM simply deletes from the backup what is deleted on the Mac.. since you obviously no longer think it important.
Actually you should read the whole thing about how TM works.. as it thins backups on a daily and then weekly basis, and there is no telling when it will delete your files, once they are gone from the Mac.
You don't have to copy the existing backup.. just buy another USB drive.. a decent size one this time.. and USB3 for future use.. 2TB or greater. And start a new backup to that.. Include the iphoto library in it.. but also copy the files manually so you have a backup unrelated to Time Machine.
Actually I would spend the money and buy Carbon Copy Cloner (or like backup software) as it does a better job of creating a backup of your files. You can also make a bootable clone of your existing hard disk.. that is hugely superior to the way TM works to get a dead drive computer running again.
Learn the lesson.. we all have to lose something before the knowledge we should backup is hammered home.. it is just sad it is digital photos which are so valuable and irreplaceable.. No amount of backup is too much for digital photos.. you are a few seconds from disaster and losing everything once you move away from films and negatives that can be reprinted for years and years.