I'm in 8b and grow citrus in pots that stay outside. It is possible. The Meyers Lemon has done well for years in a huge Marshall's Pottery pot. The lemon is near the end of its life now, but has been left out in winter for many years. I just cover the plants and pots with old blankets and/or frost cloth, depending on the weather.
You have the best authority on citrus selection right in your backyard! TX A&M could give you the best advice through their website, or even a phone call. Try the Master Gardener desk at the Extension office too. They can send you printouts of good information on growing citrus in your area.
I have a few grapefruit this fall that are nearly ready to pick. I don't eat them, just wanted to see if I could grow them in a pot. Our soil is too alkaline to grow fruit in ground.
There's article about growing citrus in containers on the front page of NGA today,
@teacup754 .