Opinion on suit and where customize it

Just in my opinion, the slim-fit seems to be better for your body. :-)

The shoulders are terrible (pitch off and not compensating for imbalance). Also, the jacket might be too tight around the seat. It might not be possible to fix much of the shoulder problems.

This is a dreadful looking thing.

It appears to be cut too tight to the waist and then it flares out even causing the pocket flaps to flare. is that just a single button on the sleeve? You spare us the trousers.

Sleeve pitch is a joke. I would hate to think who made this for you but it might be a courtesy to name and shame so that others can avoid him.

It's possible there was some weight gain after the measurements were taken.

Welcome to Styleforum Leader12
Personally, I would toss this suit altogether. There are just too many issues with it.
(shoulders too wide, too much waist suppression, too wide in the front, button stance too high for your body type, sleeves a tad too long)
Also, what could be throwing things off is your posture. You are slouching. I would like to see a reshoot with you standing up straight, shoulders back, chest out, chin up. Relax, don't slouch.
Hopefully Despos or one of the other tailors will ring in on this.

I would not say that a slim fit suits you better in general. In opposite I would suggest you to try a three button sack suit. This style might be adequate for wider trousers which might be more comfortable for you. The jacket further must especially be quite longer. Leave this one as an experience and save for another one ;)