Jamie Lynn Spears "officially engaged" to boyfriend Casey Aldridge

Jamie Lynn Spears is officially engaged to boyfriend Casey Aldridge, and the pair are planning a small ceremony in Spears' hometown, Kentwood.

"Jamie Lynn and Casey are officially engaged," a friend of the teenage couple tells OK! magazine. "They're committed to each other and anxious to be the best parents they can possibly be, and also the best husband and wife they can be to each other."

The 16-year-old actress -- who turns 17 on April 4 -- is expecting her first baby in late June with Aldridge, and is happily riding out the last months of her pregnancy with her beau by her side.

After Jamie Lynn -- the sister of Britney Spears -- announced the details of her shock teen pregnancy in December last year -- she has been busy lying low in her hometown of Kentwood, La. And Jamie Lynn and a cousin recently registered for her baby shower at a Babies 'R' Us store in the nearby city of Baton Rouge.

Sources close to the teen star say Jamie Lynn plans to marry Casey it Kentwood at "Serenity," the estate owned by Britney.

"She'll have the baby there, and soon after, she will also get married there," says a pal of the teen. "I expect she'll want to wait at least several months to get her figure back so she can wear a beautiful wedding gown and then have her dream wedding."