I would say get rid of the starch for two weeks (replace with fruits/veggies) and prove to yourself that they either 'are' or 'are not' the problem, I personally cant eat any start without breaking out. The problem with starches is that they are fast acting carbs which cause lots of ups and downs with your insulin levels-this in turn messes with other hormones especially androgens which are notorious for causing acne. When I eat starches I get acne, oily skin, blackheads and hairgrowth on my face (Im female so that is not good). My husband gets the same effect from starches.
Men who have these types of insulin problems are also prone to loosing their hair-any issues there? YOu are probably too young to notice though.
The other issue is fiber. You arent getting enough without consuming veggies and fruit. PERIOD! Fiber is so neccessary to keep that nasty protein moving more quickly through the digestive tract so that parasites and bacteria dont spend too much time having their fill. Plus fruit/vegetable fiber is the neccessary food that good bacteria needs to multiply. Good bacteria have so much to do with the immune system and with digestion.
I say you have no reason to be frustrated with having acne, you have not exhausted all of the possibilities, and especially one of the major possiblities-consumption of concentrated starches and lack of fresh fruits and vegetables. Cutting out starch/refined carbs and adding in fresh vegs/fruits is usually where people start when trying to clear up acne.