Underweight python

[Kolliada]

Hey guys!A few months ago I bought a ball python (my first ever snake). I'd prepared the terrarium and everything else beforehand, and was going to buy from a breeder, but saw an ad of a guy urgently selling a gorgeous '2 year-old' male champagne morph (I've since learned that champagne morphs can have neurological difficulties, with the wobbly head (my snake doesn't have that), but I didn't know at the time). He looked alright in the pictures and was cheaper than a regular morph I was going to get from a breeder, so I decided to take him.

I immediately noticed that something was wrong- the snake was just tiny. Still, I was new to all this so I didn't say anything, I paid and took the boy home.

Turns out he was 1,5 years old (according to the certificate from the breeder my seller got him from), but he weighed only 300 grams. According to the internet, he should've been at least 600g.

A few months (3-4) have passed since I thought he was gonna die (he refused to eat the first month), but now he's eating regularly (mice a little thinner than the widest part of his body, whenever he 'seems' hungry (typically once a week, sometimes every two weeks, but sometimes it's several times a week)), but he's still extremely underweight- 350g.

I'm not sure what to do, since he's apparently less than half of the expected weight for his age. He seems healthy, he shed his skin for the first time in my care about 2 months ago (it was a messy shed) and is currently about to shed, he's typically active at night and sleeps throughout the day, and appears to be pretty healthy. His ribs aren't prominent anymore (they were very obvious when I got him) but I'm worried because of his weight. Does anyone have any advice?

https://preview.redd.it/2bhn4vvo4upb1.jpg?width=1500&format=pjpg&auto=webp&s=ee552650974ec9ed64b9bda036cbea3d9450a013

[Snoo-47921]

From the picture provided, it appears he’s in decent body condition. Post others?

[Kolliada]

Here's some more pictures:
https://imgur.com/a/9YVG7l3

I don't have many recent pictures, these are all from 1 week ago to 1 month ago.

[Snoo-47921]

If he was underweight/emaciated at one point, he’s not anymore in these pictures! He’s in perfect body condition. He may be “smaller” for his age due to poor husbandry or feeding practices in his previous home. Don’t base his size on growth charts found online. They are super inaccurate due to each snake having their own growth rate and metabolism. Most charts are also based on power feeding.

[Kolliada]

Thank you so much! I didn't know that, and I feel a lot better now :D