Hi Amy! Barb has some great suggestions there. Throw a little change up into your regimen with some calorie increases and then decreases every couple of days. Give that exercise a change-up...above all, be persistent! You will see it pay off after you get past this little plateau.
Welcome. You may have reached a plateau. Try changing your eating habits a bit - decrease your daily calories by 100 or so, then increase them. Make sure you eat a wide variety of food.
Also try changing your exercise regularly too. If you do the same workout every day, in exactly the same order, your body gets used to it and it's no longer a challenge. I'm not sure how old the step children are, but you live in an area where it's safe, why not try putting the baby in a stroller and get the other 2 children and go for a walk a couple days/week. Just keep mixing it up so your body doesn't know what to expect.
Good luck and keep posting. Let us know how you are doing.