If the suit is OTR there is probably about a half inch AT MOST at the side seams of each vent that you can let out (Unless their seam allowances are nice and wide). The jacket is not tight at the CB seam around the seat indicating that there isn't sufficient fabric at the front of the jacket only. The fix for this is letting out at the side seams the front part only on both sides. This will shift whatever extra fabric is inside the seam allowance to the front of the jacket only. If you let out the side seams at the front and the back it will cause the back to be a little messy. This requires a fairly competent tailor as the double vents can be affected, especially if the lining isn't redone right. Also, were you forcing your arms down straight in the side pose? The sleeve pitch may be fine if you're forcing that pose but it's also an issue. Sleeve needs to be rotated forward nearly .5". This is another significant fix and it's never really perfect on any RTW jacket. If you've got erect posture, you'll naturally have a shorter back and just about any RTW jacket you wear will have backwards pointing diagonal drags from the shoulder down the sleeves. This is because most RTW jackets are allowing fabric for a "natural" length back and front. The opposite occurs when someone has stooped posture. The back is too short and front is too long.
From the front, the sleeve length is too long. You can see it in the breaks forming down the front of the sleeve. If those buttons are functional and you want to shorten the sleeve, it has to be done from the shoulder. This is tricky business but if you're gonna do it, you might as well get the sleeve pitch fixed as well as the sleeve has to come off. There is excess fabric at the top back of the jacket. You can see it in vertical folds. The fix is in part at the CB seam and in the back parts only at the side seams perhaps even into the arm holes. This would clean up those vertical folds you see at the upper back. Your posture appears to be erect. You could possibly square the shoulders slightly which will shorten the back enough to improve the balance but it's not that bad.
Last but not least, it looks like the pants could also benefit from a slight adjustment to the crotch and stride (The inseam needs to be taken in from the knee up .5" on the front part and back part of the legs). This will fix the droopy crotch and vertical folds down the back of the leg.
If you want this suit to look totally right you can expect to spend a good bit of money. If you brought it to me I'd charge you nearly $150(+/- $25) easily to do all the above mentioned alterations (not suggesting you bring it to me). You definitely wouldn't want to take this to an amateur tailor or be in a hurry to get it done. Depending on what you spent and what the store's policy is, you may be able to get a return or perhaps an alterations credit?
Hope this helps.
