I went back to work when DD was 16 weeks old, as I'd started with my employer when I was pregnant and felt like I owed them something.
Everything went great and I went back to work 2.5 days a week. It worked out well for all of us.
When dd was 4.5 I had my 4th miscarriage and decided it was time to take stock. I took a 5 year carers break and am due back when DD is 10.
I love being able to drop her at school, go on school trips, not worry about training days, etc. I always offer to help working mums at the school and usually have an extra child on the odd days when the school closes. I know how hard it is for the workers out there!
I trade on Ebay to keep an income coming in. It's hard work, looked down upon in every way by my middle class peers and dismissed out of hand by everyone but my DH.
We take in a good amount of money (if you don't work out my hourly rate which would be SO far below minimum wage it would deny reason!) and I have the flexibility to cope wiht illness, unexpected closure days, playdates, etc...
We haven't had to adjust our lifestyle too much. We manage quite well and I love the freedom of my SAH job.
Personally, I would find going back to work right now so hard. I'm not even sure I'll go back when dd is 10 as I have the perfect life right now. Time is a bonus; husband likes me being home, but doesn't expect the house to be a palace or expect his tea on the table when he gets in. We have a joint account and I spend what I like (though we're currently trying to pay off the mortgage so I'm trying to keep spending low).
You have to consider your options really carefully before making your changes. There are 'down' points to the SAHM lifestyle. Your social standing in the eyes of most working mums is zero. Your income is obviously depleted, unless you can replace it somehow like we have. You can be a little isolated/insular. But if you make efforts you can connect with your community in loads of ways.
Good luck, whievhever path you choose. Personally, I have so much admiration for WOHMs, juggling jobs, kids, school, social diaries from hell, etc....
But...I wouldn't dismiss being a SAHM too easily as it's a beautiful time of life that's hard to regret! And you can always go back to work if it drives you nuts