K.N.
First things first, learn to delegate, your 6 year old can help out with simple shores if he doesn't already, and so can your husband, just because you are home all day does not mean you have to be the only one caring for the kids and cleaning and cooking. My kids 10, 8 and 6, make their own beds, feed the pets, dust and sweep their rooms, put their clothes in the hamper and their dishes in the dishwasher. It's amazing how helpful this is. My husband also has a few things he does before work, like emptying the dishwasher, sweeping the kitchen and folding clothes.
Wow it seems like i don't do much huh?!
Second set up a schedule for work just like if you had a regular job, get a sitter or whatever you need to do in order to go to work. Use this time to work, not clean the house.
Third have realistic expectations, if you only dust and vacuum once a week that's alright. If laundry sits folded in a basket till saturday no big deal. little things like wiping the bathroom counters down after your shower, and making sure things are picked up will make all the difference.