HELP, i have feeding issues

okay so i got my BP about a week and a half ago its between 16-18 inches (i havent gotten a scale yet) and the pet store lady said to feed it pinky mice, i fed it one, and he ate it no problem but he ate it backwards and diddent constrict it first just bit it held on for a second and started eating, so after some research on th fourms i found that pinkies are too small so i switched to fuzzies today, it did the same exact thing again this time ate it very quickly(id say i couldent see the mouse after about a minute or so at the latest) and he diddent constrict and ate it butt first again, so should i be feeding larger mice or more?, and is it bad that hes not constricting his prey and has eaten these meals backwards? please help this fourm has answerd all my questions about set up and so fourth so far so i know someone out there can tell me whats wrong, thanks
~cylis

Sadly you were provided with erroneous info, pinkies are indeed way too small for any BP (hatchlings are usually started with hopper moving quickly to adult mice) which could be one of your problem.

If the prey is too small the animal will not always recognize it as a prey and if it does because of the small size it will likely not constrict it.

Lack of constriction and eating backward are not something you need to worry about.

Simply offer your BP and appropriate size prey, something equal to you BP’s girth size (widest part of your BP’s body) once every 5 to 7 days.
Good luck.