Looks all right to me. I would get used to the flapping. You may be used to wearing jeans. If you taper, the flap will diminish but the trouser opening against your shoe won't look as good, This is purely opinion.
Terpo, you do not have sloping shoulders. The left shoulder is sloped too much. I imagine you feel pressure on your shoulder point from the jacket. You can see how the jacket falls away on the left side more than the right. The left jacket edge is farther away from your shirt placket. The shoulders are a little funny, you need the collar to sit higher in back.
You may have a bit of a balance issue. Need longer front/shorter back.
It's the circumference where the jacket buttons. Above this is the chest in front and blade in back. Below this is the skirt of the jacket.
When you have the waist taken in, the tailor reduces the amount at the side seams to make the jacket fit closer to your body or to create a shaped waist.