Yellow Bellies can be sort of hard to pick out sometimes... but, to me, neither the OP's snake nor Anatess (sorry ) look like one to me. (Not making any accusations against any breeders, just calling it how I see it.)

These are the things that I look for with a YB:

1. Flaming
2. Head spot (not always well formed)
3. abberant belly

I made a similar post a while back with pictures of my two... I'd also like to point towards the Hunter's Guide to YBs.

Here are my animals:

They vary in color a bit, but they both have flames that creep up the sides:


They both have head spots:


But the big thing here, is their bellies... Eros has a white belly but you can still see on the edges the 'distortion' of the color. Psyche, on the other hand, has a very yellow belly with the same distortion on the outer edges:



No black or grey track marks up the middle of the belly.

I hope that helps on what to look for. YMMV