Weight gain before seeing surgeon for upcoming surgery

My anxiety is at an all time at the moment. My surgery date isnt until October 30th and I start my liquid diet October 16th. I'm not stressing about the surgery but the weigh in with my Surgeon. She wants to do a weigh in on Tuesday October 17th but the probably is I gained 15 lbs!!! I gained all that weight in 5 days. There are a lot of factors... 1) I didn't drink any water for 3-4 days 2) My period has been on and off for 2 weeks because the birth control in my arm was expiring so I got a new one put back in 3) stressed 4) lack of sleep and going to bed super late. I know you can gain some weight from water retention, being on your menstrual and being stressed out but 15 pounds?! This is really bad timing. If im not the same weight or have lost anything that means my surgery will be postponed and that isn't an option for me. I plan on starting my liquid diet a little bit in advanced ( Sunday 10/15 ) This has to be all water weight but i don't know if it's possible to lose 15 pounds in 3 days. This is all just bad timing