I vote your builder as the worst in America. If you look at the pic "from below" you'll see that: 1) the truss spacings vary, 2) the shingle nail spacing vary, and 3) I'm betting you don't have enough attic ventilation.
1/2" Plywood roof sheathing can only span up to 16" (in some areas of the country with little or no snow, that spacing can be increased due to what is called, "short duration loading".) That one truss spacing looks like more than 24", in which case you need 5/8" min. (By the way, I like five ply for that.) I'll bet he used 1/2" plywood and spread the trusses apart for some reason, (I.e.: miss a chimney, etc.). I'd talk to the Building Inspector about that.
From the bottom view, you can see the shingle nails are all over the place. They are not "in line" and the spacing goes from a couple of inches apart to an area where there are maybe 2-3 nails per shingle. That is not allowed by ANY roofing manufacturer. They are suppose to be uniformly spaced. No wonder the shingles are buckling. (Oh, if you want to check a really obscure thing, check the distance from the butt (bottom) of the shingle to the nail. Read the wrapper (or go on line and read the "nailing instructions".) Few roofers actually nail in the correct "line". This is important because it will warp the shingle where the nail penetrates the 2nd shingle below the exposed shingle and cause a leak. Also, check to see how many nails are required in each shingle...I'll bet it's 5, unless you're in a "high wind area", then 6.
You need 1/150th the area of the house for CROSS ventilation. Or, if you place 50% but not more than 80% in the top of your roof (ridge vent or gable end vent) if it's more than 3' above the eave, then you can reduce the amount of ventilation required to 1/300th. It looks like you have a ridge vent, but I'd check the eaves. I'd bet it's way too low.
How much did you pay for your Building Permit, which included inspections? You got robbed.