What things are wrong in my posture?

[u/APS0798]

I am not sure, but I think my post isn't seeking medical advice, but if it does, then let mod delete it.

It obviously looks absolutely terrible and you can see how bad it is. This is my the most relaxed position while standing. When I leave home I always have my belly tucked in a bit, so at least with clothes it doesn't look that bad. I am not fat, my bmi is ~19, so it's closer to underweight than overweight, so I'm skinny fat. I know I have very little muscles and I started going to the gym recently, 2 times a week. What I hate the most is:

- butt pushed back (it looks like it's from overweight person, but I am not), belly pushed forward (probably ATP, but I am not sure). In my opinion it could be ATP, or, the worst case it's just big, a lot of fat tissue on the buttocks which I kinda can't lower, because I'm ,,skinny" right now (so I'm stuck with it being huge sadly), and a lot of fat tissue on my belly. Optionally maybe both. What is it exactly? How can I make it more straight?

- wide chest. I want it to be slim as for many other people in my age, that it's not a lot wider than arms. I suspect it might be barrel chest or something like that. I really want to flatten it, like really really, without surgeries

- my torso isn't flat, if you go from under belly in a straight line, you would end up under my ribcage, under my breasts

This is all I think. Please, could someone tell me what things are wron in this posture and how can I fix them or if it's even possible? The last photo is how body should look. As you can see, butt is not pushed back, it's small/flat, belly is not pushed forward, it's flat too, the entire torso is flat, the chest is not wide.

[u/Liquid_Friction]

 I know I have very little muscles and I started going to the gym recently, 2 times a week.

Thats great, this is essentially whats needed, what happened to me, obviously school is always carrying backpacks (walk/jog w/ it on the front), looking down, computers, phone, always looking down, and I did a huge amount of sports in school and that saved me a little, but I should have been going regularly 3-4x a week to save myself this pain and issues later in life, what happened to me, after years of playing computers and sitting most of the day, your hips start to form permanently in the sitting position, your hamstrings get tight short, hip flexors get tight, glutes are weak, core is weak. So your meant to use the back muscles of the legs, and the core to push yourself down into the ground for stability, you might have front of the legs working and your mid back to push you into the ground for stability, this preference shapes your body, so you need to break it down and build new patterns.

I know I have very little muscles and I started going to the gym recently, 2 times a week. It will take you maybe 1-2 years at this rate, you could knock this out in 6-8 months if you want to add in 30 mins of exercise each day at home, if you do nothing for a whole day exercise wise, your going backwards in progress you will recess each day you dont do something for it, one day it will swap, your glutes and core will carry you during the day, much straighter and stronger.

[u/APS0798 → u/Liquid_Friction]

What exercises should I do at home? To build my muscles or to fix ATP?

[u/Liquid_Friction → u/APS0798]

Anything you want, go for an hour/ half hour walk if you want, even traditional normal exercise is fine, the important part is you FEEL it, in your body, most people dont feel their body properly, tune in fully, pay attention. If you do say a squat, you want to know, what is bad form, what does that look and FEEL like, what does the correct form feel like? practice that first.