CLRS's Fibonacci Heap size(x) analysis has a flaw?
In CLRS, $s_k$ is defined to be "the minimum possible size of any node of degree $k$ in any Fibonacci heap." Assuming your example data structure is a valid Fibonacci heap, your Fibonacci heap has a node of degree 2 with size 8 and a node of degree 3 with size 6. Thus, these are possible sizes that nodes of degree 2 and 3 can have but not lower bounds on their sizes.

Using Lemma 19.1 (as in the proof of Lemma 19.4), $s_2 = 3$ and $s_3 = 5$, monotonically increasing as CLRS claim.