The surface area and porosity of a material can be estimated well in BET. For 2D materials e.g., graphene-family, number of layers is also a significant parameter. Because for the 'same amount' of graphene, surface area is different depending on the effective number of layers. Defects also play a major role on it. To determine them, Raman analysis is suitable. I think, BET along with Raman spectra gives the complete information of your material.