Major Weight/size Fluctuation Depending on Cycle

I’m not sure how common this problem is or if this is just me. My weight and size changes based on where I am in my cycle. And I’m not talking about a pound or 2 or some bloating. Im talking about an entire inch on my waist. This puts me in between sizes for my dress it seems. Im a size 2 for my dress on a normal day usually around my follicular phase and probably a size 4 close to/around my period during my luteal phase. I already bought a size 2 for my dress. I guess I was in my skinny phase when I bought it. Since I can’t exactly control when my wedding date falls in my cycle (without birth control pills), should I just go ahead and have the seamstress change the back of my dress to a ribbon tie back?