I'm with ya! I work full time, too, and I'm currently a single mother of 2 girls. I will soon have a husband to share the responsibilities, but I'll have 4 step-children too. We are constantly on the move. Here are some things that help me stay sane:
1) Know that you're not alone. There are plenty of us working moms out there, and even SAHMs struggle with this. It's just a product of our culture. Americans are busy people, and our kids are busy, too.
2) Set realistic expectations for yourself. Your house is never going to be spotless. Your laundry is never going to be done.
3) Remember that it will get easier as your kids get older. You will gain little moments of 'freedom' when your kids can tie their own shoes, buckle themselves, brush their own teeth, take a bath by themselves, play outside unattended, flip on cartoons until the sun actually rises and you're ready to get out of bed. :)
4) Share the load. You didn't complain about your husband, so I'm guessing he's already doing his share. :) If not, though, ask for his help. Maybe he could do baths while you're doing the dishes. Maybe he could read bedtime stories while you prepare things for the next day.
...which leads me to
5) Be efficient. If possible, run errands at lunchtime. Spend a few minutes in the evening to get ready for the next day (pack daycare bags, lay out clothes, prep for tomorrow's dinner, etc.)
6) Find a good babysitter, and book him/her in advance for the first Saturday of every month (or whatever works for you). This will encourage you and your hubby to spend time together. My girls stay overnight at my parents' house every other Friday (on the weekends that we don't have my stepchildren). Usually we just run errands together or take a walk, but as you know, it's a treat to do these things without 2 little ones in tow. And we get to sleep-in and maybe go out for coffee and a bagel in the morning!
7) Give yourself a break. At least once a week, have 'sandwich night' or get pizza/take-out. Use paper plates so there aren't any dishes to clean.
And lastly, know that you are a wonderful role model for your kids. More than likely, they will have to work when they're adults, and they will be better equipped to handle the craziness because of you!
I hope this helps. Good luck!