It can never hurt to have an electrician look at it. Once you apply a safety factor, you have 1800 watts for 20 amp and 1500 watts for 15 amp(I believe). Remember 20 amp breaker on 12 guage wire and no more than a 15 amp breaker on 14 guage wire or you may have a fire in your wall somewhere. Also don't put more than one wire under each screw on a switch or receptacle. Use pigtails instead.
It is recommended to have more than one circuit in a bathroom cause you can end up with a 1500 watt curling iron on while a 1500 watt blow dryer is running besides fans, lights, heater, etc. Breakers do not always break when they are supposed to, you can have substantial heat and a fire before the breaker trips sometimes. Sometimes they will not trip with a dead short till after the arc fault has arced and caused a fire.