Mike, the NEC has an exception for residential use. They basically require a general lighting/receptacle circuit for every 500 to 600 sq.ft. They don't regulate the maximum number of receptacles although they require a minimum amount based on spacing so people don't stretch cheap extension cords all over which creates a worse fire hazard.
Except for the kitchen, bathroom, laundry room, they feel that the general circuits will just have lamps, clocks, radios, etc. which don't pull many amps. So adding more receptacles isn't against the code. That said, go ahead and calculate your present load and what else you want to put in. If you are running 1500 Volt/amps aka watts continually on 14 guage wire, then think about change to 12 otherwise stay 14. Overload it and you can have a fire. Don't forget to put a GFCI receptacle in as the first one. Final caveat is check with a local electrician and get a permit. Some places allow people to work on their own home and some don't. Good luck.