After my first was born, I was only working part-time evenings as it was, so it was no different for our financial situation. I worked two jobs after my second was born (I had to go back to work when she was 2 weeks old), and promptly re-evaluated things. Luckily, my husband is paid well enough for me to be a full-time mom (it's not great, but we're comfortable).
I completely understand your desire to stay home. Some people will say it's just cause you're a new mom, which is true in part, but these days fly by so quickly! Don't let people try to talk you out of your decision. Do what you and your husband feel is right for your family. Personally, I couldn't do the opposite shifts with my husband, I need our personal time as much as my time with the kids. After Baby is born in December, I'll reconsider going back to work, but for now we're fine, and I'm thrilled to be with the kids.
On the flip side, once you DO leave your child with a sitter, the first week or so is tough, but it gets so much easier. I had more separation anxiety than my son did. :) Plus, he met so many new friends and just took off developmentally that I'm glad I placed him in daycare. (we had a phenomonal daycare provider)
I'd say give yourself a month back at your current job and see how things go. If it still doesn't feel right, rearrange your schedule or find something that will allow your family the flexibility you need. Congratulations on becoming a Mommy! :)