Hi Tina, and welcome.
I’m sorry to hear that Marlena has reflux. 
My son was diagnosed with reflux at 6 weeks and we also started out with zantac & reglan (metoclopramide). They worked for awhile, but then stopped working. After that he was put on Prevacid, and that made a huge difference. So you might want to try getting your daughter on a PPI medicine like Prevacid. Most babies seem to do best on a PPI.
Good luck with the Upper GI. I hope you can get Marlena to drink from a bottle! My breast fed babies would never drink from a bottle either. 
Bryce has a feeding tube, so we didn’t have that problem when he had his upper GI.
Good luck with everything! I hope you can find something to help little Marlena feel better soon.
