Is an eye infection painful all the time?

So, I wear contacts that are supposed to be changed every month...and I am now on about month 15 or so of wearing them. Stupid move, I know!! Anyway, the buildup on the lenses has gotten to the point where I can't really see all that great with the contacts in, so I've finally just taken them out and will be stumbling around blind until my eye doctor appointment next week. I've read that wearing contacts for too long can cause eye infections, but I've also read that any discomfort may be due to the buildup itself and that there is not necessarily an infection present. The only time I experience anything resembling symptoms of an infection is when I'm wearing the lenses -- watery eyes, feeling like something's in my eye, etc. As soon as I remove the lenses, my eyes feel great -- no redness, no tearing, no issues other than the fact that I can't see because my natural vision sucks. If my eyes aren't uncomfortable without the lenses in, is it possible that there's still an infection?