Then try and find another shop other than Harry Rosen that sells Coppley. Most other high end clothiers do. I know for a fact you can get a made to measure in a 34" chest. You are not grossly disproportianate, so made to measure should be fine. Coppley has a 3 week turnaround and they also make odd sizes like 35, 37, 39, etc. If you fit a 35, and it still fits OK on you, then that gives you some room to grow. Same with the pants. Might want to order a 30 waist so that it can be taken out to 31. Ideally, you want an exact fit, but at your age, you're still filling out. The jacket will only be half canvassed, but most people can't tell the difference.
Go with a plain medium to dark grey. It can be used for social and work. Don't get black as your first suit, especially if you're a white boy. Too stark in daylight conditions, and everyone in food service wears black and white. Don't make your suit a signature piece. You can make statements with your cheaper tie and shirt.
Get decent shoes. No square toed Kenneth Cole slip ons. Dressing sharp is the total package.
Youtube is your friend. Look up men's suits on youtube.
Harry Rosen also has information videos on youtube which show you how a suit should fit and starting a wardrobe.
