Syrena, just try the tail on first before you trim any scales. It may fit just fine. My tail is I think 2-3 inches smaller than my measurements and it fits me fine. When I was doing the measurements, Abby and Bryn told me take off an inch all around anyway, to account for the stretchiness of the silicone and keep it snug around your waist so it doesn't gap. This works very well. They took off an additional inch from my measurements because at the time I was doing a workout competition with some work friends and was losing a fair amount of weight. Well, I didn't lose much more after that but oh well :P Still fits.

If you do trim scales, make sure to be very careful and round all the corners between scales. Do NOT make a cut down into the tail between the scales. This will just give it a place to tear from very easily. Yes, Dragonskin is very durable but it is not indestructible, and if you give it a pathway to tear on a high-stress area like the waist, it definitely will. I had a small tear in the waist of mine due to this, because there was an area where the point between the scales was too sharp. Luckily I was able to fix it easily (well, Lorelei fixed it for me, with a little more Dragonskin). Anyway, you just want to be very careful with that area. That's why I lowered the waist of mine a tiny bit, to take a little pressure off it when I pull it up over my rump.

And I can't remember if I posted this before, but here's a video of me swimming in my tail (with Mermaid Lorelei who is awesome and who made the video). You can see how it fits me and how the fluke moves in the water. I have more video clips but I'm clueless about video editing so I've done nothing with them so far It's also the first stuff my husband and I were shooting with our GoPro so it was basically a practice run. I need to get some more footage and learn video editing...