I work for a company that outsources customer service needs for utility companies.
You cant really compare this months bill to last months bill to get an accurate idea of your use, it has to be year to date. weather is the biggest impact because of ac and heat, and your little lights do nothing. \
if your curious how much power your grow is costing you, its really quite simple if you know where your meter is.
first turn the breakers off to everything in the house, give the meter 10-15 minutes to stop turning, and read your meter.
turn on the breaker only to the outlets for the room with your growbox, and make sure nothing else is plugged in, turn on your grow box systems, and wait about an hour.
read your meter again.
subtract the difference from your previous reading, if your meter has a multiplier (usually 1 or 10 for residential service) multiply the difference with that number. this product will be the number of kwhs to run your box per hour.