Is Whitney Houston's Only Child Bobbi Kristina Married To Her Adopted Brother Nick Gordon?

Bobbi Kristina and her adopted brother might now be married, after a year of being engaged. Bobbi Kristina posted a picture of their wedding rings on her twitter.But i didn't see any congratulation messages on her twitter, so it is kind of confusing if they are married or about to get married.
Nick Gordon was adopted by Whitney Houston when he was still young, Bobbi Kristina and Nick Gordon relationship was revealed after Whitney passed away.
See another photo of her ring below...