I think the hair you have is very pretty but if you think you'll like the bob more go for it. That girl on the right does have very thick hair. If you want to go for it try a little longer bob and if it doesn't look to bad you can have it cut shorter to the bob in that picture. It's better to not have enough cut off than having too much cut off.
Thin hair gets more volume when it's shorter... so yes, I do believe your hair would look much better shorter. To that length in the picture exactly might be the perfect thing for you. Your hair would also hold a curl better and longer. =)