This paper presents the study on power scaling of an all-polarization maintaining (PM) fiber mode-locked laser using the multilayer chemical vapor deposition graphene/poly(methyl methacrylate) composite as a saturable absorber by changing the coupling ratio of the laser output coupler. Pulses with the duration of 148 fs were generated using 10% output coupler, which are the shortest pulses obtained from mode-locked erbium doped fiber laser working in anomalous dispersion regime, additionally the highest average output power of 15.66 mW was achieved by applying 70% output coupler. All-PM fiber resonator configuration provides self-start and stable operation. To our knowledge, this is the first comprehensive study of power scaling of erbium doped fiber laser with graphene saturable absorber. Conducted experimental work is in very good agreement with numerical simulations.