"Overcarbed" is relative. Some beers should be low to moderate carbonation, and some should be quite high. Some can be near champagne levels of carbonation. It all depends on what you're trying to achieve. Most homebrewers (especially new ones) slightly overcarb most of their beers.
If you've given the beer proper time to condition (which you pretty much have, another week or two may help, but you're probably about where you're going to be), and enough chill time to dissolve the CO2, and it feels too carbonated to you, then yes, it's probably overcarbed (relative to what you want). I find the 5 oz corn sugar per 5 gallon batch ratio that's often used with kits (or adjusted relative to other batch sizes) too be way too carbonated for my tastes, and too carbonated for most beer styles. Check an online priming sugar calculator, and factor in the actual bottled volume, not batch size (I assume 10% volume loss to yeast cake, ie for a 5 or 5.5 gallon batch, I subtract 0.5 gallons from the fermenter volume and calculate for 4.5 or 5 gallons respectively), temperature of the beer (I go by the highest that it reached during fermentation, but temp at bottling would work too), the level of CO2 you want (charts out there, but generally bottled English beers are ~1.5-2 volumes, American and German lagers/hybridgs 2.3-2.5 volumes, and 2.5-3.5 for Belgians/sours/Weizens).