J.,
I totally feel your pain! With my son it took me over a year to get back in shape, let alone lose any weight. I can't afford a gym membership, and I hate running anywhere.
What I did first, was starting walking with my baby...put him in his stroller for his morning nap and walked around my neighborhood. There are lots of places you can go walking and over time that helped me start getting toned again, and burned calories.
Second thing I did was bought an exercise/fitness ball at Target for like $10, and a set of 10lb. free weight...and then, found a workout that I could do while my son was napping in the afternoon or once he was down for bed.
This is the workout I still do a year later at least three times a week...
http://exercise.about.com/library/blbeginnerball.htm
Now that I work full-time and my son is 2.5, there is even LESS time to work out...oh, and I'm a single Mom too. But, I try to fit it in at least three times a week and try to get out with my son at least once a week to a local park or just down to the grocery store. Get out of the house with your kiddos, you can even make them a part of the workout by buying a kids workout video and having your five year old do it with you!
Don't worry it will get better!! Just take a deep breath and find what works for you. The most important thing is not to defeat yourself before you even try. It took me six months to get toned once I got started and stuck with it, and now I feel great and am not super thin but feel good. Don't rush yourself and don't give yourself unrealistic goals to meet and you'll be fine.
Let me know if you ever want to chat!
____@____.com
D..