Holding water for ultrasound

Okay so my doctors office, like many others, requires me to drink and hold at least 24 ounces of water 45 minutes before my appointment. When I had my last ultrasound at 8 weeks, I was in SO MUCH PAIN from my bladder being so full and I could barely walk. Does anyone know if this is normal? And if so, any advice on what I can do to help this? I have my next one on the 13th. Can I get away with less water/not drinking it that long before my appointment? I’m just so anxious about it because I don’t want to feel that way again, it ruins my excitement of seeing my baby. 😭