Before rushing her off to a vet, give her a couple weeks in her new home and get her eating for you. It looks like you have her in a tub, which is great. I agree she has "sausage butt" which probably means she needs to poop. I noticed that many of my new arrivals would release that poop within a day or two of getting setup in their new home (when they finally can relax...lol).

As for strength, it seems to vary for BPs. Out of the 6 in my house, one of them was a similar runt at 2 months old and only weighed 66 grams. Even at that size, he was the strongest of all my snakes (even a firmer grip than snakes a year older than him) and also the most efficient at killing his meals. In comparison, the other 2 month old Mojave I got from the same place was fat and healthy at 100 grams at the same age and would not grip at all and would fall off your arm in a heartbeat if you let him. He's gotten better as he has gotten older. Remember, they are just babies and have to learn how to cope with their environment.

As for my little guy, after moving him to a small tub (15qt) and covering it with a cloth during the day, his entire temperament changed and he began consistently eating. Now he's up to 115 grams less than a month later and is seems much happier and healthier.

So get your husbandry spot on and let her settle in.