Make your peace with the laundry...you'll never catch up, because you always create more. I try to do a load when I can during the week or weekend, and hit one day where I do six loads.
As hard as it is, what you need to do is find SOME help...just for a weekend...a friend, your husband, someone from church, whatever...to take care of your son (in your home, so you can be there for support) and dedicate the WHOLE weekend to your house. Start in one room, take some laundry baskets or boxes, throw everything in that doesn't belong, rearrange furniture, clean thoroughly, organize, etc...then move to the next room, deposit whatever you've found that belongs there, and repeat. I do this two to four times a year, and it will get you ahead of yourself. It'll feel so good to get it done...and maybe you can do it in one day. Sacrifice one day (as hard as it is, believe me, I understand).
Also, if you clean more frequently, you save tons of time. Wipe down the sink/shower after using it, etc, and you don't have to deep clean as much. When you're just sitting watching your son play, or whatever, dust the furniture in that room. Fold laundry while watching TV. :)
And I hear you about the weight thing. I don't have a single spare moment, and it's depressing. I used to be so fit and thin...now, I could stand to lose 30 pounds, but it just won't go because I don't have time to exercise. Also, I haven't had a moment alone with my husband in over a year (baby with special needs, lots of illness, but doing so much better...we also have to follow a dairy free/gluten free diet for her.)
That's my best advice, though...having a clean, organized house helps your peace of mind. :)