I'm not pregnant, but when I was prenatal yoga was offered at Medical Center of Plano for about $10 a class. I'm not sure of the days, but it is a small class that is closer to your home. Also, Peppermint Boutique in Richardson was offering prenatal yoga for $15 a class. You might check them out. Both were small classes where you could get to know the other moms-to-be. Best wishes!
I also want to recommend that after the baby is born, join a group of moms with babies the same age as yours. I went to the MOM (Method Of Mothering) class at Medical Center of Plano after my daughter was born. You don't have to have given birth at that hospital to go to the class. We met once a week at the hospital. The nurse who facilitated brought in speakers for each session and we had time to talk among ourselves as well. Our group still meets three years later and it is the BEST thing I did for myself.