Hi Lucie,
Your hand is really lovely! Very consistent, nice forms, and has a lovely flow. I would suggest working on the curves (overturns) of your m’s and n’s. Also, your connection strokes off the m and n. They are very rounded and slightly impact the integrity of the shape of the letters. It is really mild (and does have a certain charm to it). But if you are looking for things to work on, I would start there.
I did a diagram for you with 6 steps to improve your m’s and n’s.
1. Your overturn strokes start too high. They should start at or just below the midline. Starting just below gives a nice entry and usually results in a line that stems at the midline.
2. The overturns should be less rounded but not flat. The upward stroke should have the *slightest* curve to it.
3. There is not enough shade at the top of your last strokes on both m and n. The shade should mirror the other shades with equal distant entry and exit at the top and bottom.
4. Lifting your pen at the baseline (and creating an invisible seam) will help keep the shade equal as you will aim to stop at the baseline, lift up, then continue on.
5. Study this diagram. The shades (the shapes in the center) should be equal and the same shape.
6. The first stroke of the v and the second stroke of the n, third stroke of the m are all the same stroke.
I think if you work on just this one thing, you will really see a difference in your already beautiful calligraphy.

P.S. I love your watercolor work!