GFCI outlet 15 or 20 amp

Hi, looking to replace my GFCI outlet & Light switch in the bathroom, both are in the same box, only 1 outlet in bathroom. Looking in the service panel the breaker is only 15 amps connecting multiple outlets throughout, when i took the bathroom outlet cover off i noticed the GFCI outlet is rated at 20amps, i bought a 15amp outlet so now wondering if i should return or & get a 20 like the old?