Oh I hope she finds a new home, maybe now people know where you are located you may have more luck - fingers crossed. I know you said you tried the Boxer Rescues but thought I would post the ones I could find in Texas just in case you missed any
Legacy Boxer Rescue
Lone Star Boxer Rescue
Austin Boxer Rescue
NorCal Boxer Rescue
Boxer Rescue and Adoption
Texas Boxer Rescue
Houston Boxer Rescue
Thank you so much for taking this girl in and trying to find her a new home, best of luck to you both.