"These are are the most recent pictures I have of him (taken last night when he was stealing my earbuds)
http://imgur.com/RC3j0Zq
http://imgur.com/QZZVsx1
Im not sure how helpful these are, but you can see his neck and spine. If you need more, I’ll send more."
From what I can see he looks to have normal weight. I suspect you are trying to over-feed him, thinking he should be bigger & eating more
than what is realistic for his age & size. A better shot of his body would help, but I think mostly this is a perception issue on your part, and
packing excessive weight on a snake is no better for them than it is for us. I'm sorry the feeding chart didn't show up (I was afraid of that),
but it's all over this site & you need to refer to it.
Feeding chart is in this thread:
https://ball-pythons.net/forums/showthread.php?243687-Ball-Python-Feeding-Guidelines