For photos I would go with a 3 color theme but pick a brighter accent color for you and your boy.
For example, you have brown boots and blue jeans. Dress boy in a brown or tan pant to match your boot or put him in a jacket with brown or tan. Dress him in a shirt with blue to match your jean....maybe a blue and red plaid and pick up the red in your blouse......
For our family photos we chose a black red and blue combo....primarily black with cranberry and dark blue accents in different plaid shirts. Turned out very nice.
I think they key is to go together without being too match match. Neutral with a bit of color what ever color you choose.
