Having trouble starting

I've had this car for 4.5 years. Originally it used to take two to three tries before it would start but only when it was extremely cold or extremely hot outside. Didn't bother me so I didn't worry too much over it. Early 2012 it started getting worse. At first it was one out of every 3 or 4 times getting in my car it wouldn't start and after 2-3 tries it'd start and run just fine. NOW, every single time I try to start my car it won't. Sometimes it take 6, 7, 8 tries or more before it starts. The car lights up, the battery is brand new, the starter isn't clicking, when I turn the key it just turns with no response from the car. It shouldn't be the spark plugs, they're still fairly new, its not the gas cap (Autozone told us that as our problem), the oil is changed regularly if not as often as it needs to be.
Before we spend an ungodly amount of money we don't have trying to fix this car, does anyone know what this could be! Please, I'm dying here.

(oh, also in the past month my engine has started... Well its not clicking but its not making the pretty hum it used to. Its like a thrumming noise [best description I can come up with]. Well it's started doing this in the past couple months, where it used to only happen for a short minute after the car was started it now sounds like that the whole drive and worse when I accelerate)