She looks good, and I like the head muscle on her and don't think it looks too small. Interesting topic because I read a study on the correlation between head size and prey size. I can't remember the link because I was digging and digging and then fell upon it. Prey size will NOT increase the bone structure in the head or cause the skull itself to grow more according to the study.
But the muscle in the jaw will develop more rapidly and become bigger which will make the head look bigger where the jaw muscles are. This can be different from snake to snake obviously. Personally I like a good thick head and neck tie in on boas.
The pin head thing Evenstar mentioned drives me crazy. It looks all wrong and so disproportionate.
For the size of you snake, her head looks fine to me. The shot of you standing with her looks very proportional.