This is an unusual minuet. First, I would like to draw your attention to measure 3, where on the third beat, three Fs create a sense of cadence, as if modulating to F major. This compositional technique, in fact, is not ideal; the outer voices (soprano and bass) descend in the same direction, forming octaves. While less problematic than parallel octaves, it is a technique best avoided if possible.

From measure 4, the same melody as from measure 1 begins again, and although it does not end on F this time, it gives the impression of the dominant of F major.

In other words, this minuet is structured with phrases progressing in "three-measure units."

The only section that does not feel like a three-measure unit is measure 9 within measures 7-9, which gives the impression of being "mid-way" with more to come. However, if we forcefully consider this as a three-measure unit, measures 10-12 neatly conclude.

Subsequently, measures 13-15 and 16-18 also form coherent units.

Therefore, while it is permissible to consider measures 7-12 as the sole six-measure unit, you should primarily try to construct the piece by thinking of it as progressing in three-measure units.

On the other hand, the Trio section progresses in four-measure units.