Snake Thin/skinny should I feed her bigger food?

Hi everyone I'm new this forum.
So basically I got a snake from a guy who gave up on her because she "wasn't eating" she was born Mid November so shes was about 4 months old when I got her 11 days ago and only weighing 62g. With him, She had only eaten 4 times in the 4 months she was with him. He says all those 4 times were assisted feedings with mice fuzzies & that she wouldn't eat on her own. Well I have no idea what he was doing or if he was lying because the very next day after she was in my care she ate a f/t fuzzie on her own, strike, coiled and ate like a champ. I fed her another one 4 days later and she ate again. Now problem is a Mice fuzzie looks really small for her. it doesn't leave a lump in her at all. But an adult mice might be too big. I'm not sure because the adult mice is only slightly bigger than her widest part but way way bigger than her neck, she has a very small neck (and I've read some scary horror stories of a BP skin stretching/ripping like a window because of prey that was too large). The petco by me only sells pinkys, fuzzys, then adults. not that in between hopper size. So I'm not sure wether to keep feeding her fuzzies but more often or to just give her an adult f/t mice. I know I have to eventually transition her to rats (I'm in the process of finding a good source for f/t rats) Shes weighing in at 77g now. shes so thin and small especially for a 4 month old female. I just want get her weight up she has loose skin and such.

She's too small to take adult mice, but you could definitely feed her two fuzzies in a row. Just feed one, wait until it is swallowed, wait a few minutes, and feed the other one. It's best to feed an "entire meal" within the same day, not spread out a few days apart.

Though if she has already been eating consistently with you, I would order rodents in bulk online. It's much cheaper and better quality than petco, and you can get the sizes you want. She should be eating hoppers.

Big Cheese has the best prices: http://bigcheeserodents.com/

I would try to find a source for weanling mice. That is what my skinny gal is on currently (she was 50 grams when I got her). Check for any local mom'n'pop stores or try to find a facebook group for snake enthusiasts in your area from whom you might be able to buy appropriately sized prey.

I wouldn't up the prey size just yet, and maybe go to a 5 day feeding schedule for a few weeks til she's eating regularly. Then in a few weeks, if she's eating regularly, weigh her and re-evaluate the situation. What's most important is getting her eating regularly. Once she's eating regularly and is putting on some grams, then maybe up the prey size.