I've never had a dog until now. What breed do you guess she is?

We adopted Lu from a rescue that brought her up from a kill shelter in Alabama to suburban Buffalo, NY. We chose her to be a companion to my husband, who at 43, has had 2 cancers in the last 6 years. No one knows where to place her. I've heard beagle mix and shepard mix the most. She stands about 2 feet tall at her shoulders and she's about 40lbs. People think she's a puppy because of her size but the shelter guesses her to be about 1 1/2 years old and fully grown.

Thanks for any of your input.