How Long Does Anti Rabies Shots Effect Last?

Hi, i was bitten by a dog last febuary 2011 and i went to a doctor and they gave me the anti rabbies shots, anti-tetanus and the immune thing.. today i was bitten again but this time it didint bleed, well im not sure because the bite was as small as a mosquito bite, its not bleeding but its color reddish. Im worried if the immune shot i took last febuary-march is still intact.