EDGE is only an new set of features that are implemented on top of GPRS.
So you are not using EDGE (this “EDGE” is just a concept), but you are using E-GPRS.
E = EGPRS
G = GPRS
G means that the area where you are in does not provide the new set of features. Probably because the sector covering your MS wasn’t upgrade with the new hardware.
The most important feature is the usage of a new radio modulation (8PSK), instead of GMSK, which vastly improves the bitrate.