Time Machine Back Up External Hard Drive Problem

Ok i as planning to sell my macbook in the near future and i wanted to back up everything to my external hard drive. I heard of offsite backup but i didn't plan on doing it yet. Anyways i used time machine to make my external hard drive to be my backup disk. First i had to take everything off it (80GBs worth of music, movies and documents) and i put it on the desktop cuz Time Machine said something about incompatibility and i had to erase my external drive first. I then backed up at least 120GB of content altogether to the external hard drive. I checked my external drive and found out the stuff i took out and put on the desktop was NOT backed up. So i deleted the backup and put the 80GB of movies, music, etc stuff in a folder in my computer.

However i can't back up to my external drive anymore. It says it only has 61.28GB of memory left. I'm wondering why is that if i deleted the backup already! I then tried to take the backup out of the trash and put it back in the external drive and it won't go in because there is only 62.28GB of memory. I don't see any partition of any sort on my external drive, no folders, files or anything yet it has magically lost 190GB of free storage. Can someone give me advice?! Thanks!

 

Oh nevermind i erased my external hard drive from disk utilities and i'm backing up the right way. Sorry!