I got to say... Reading your post it sounded like you and I are in a pretty similar situation. My husband and I are both wondering whether or not to have kids but for different reasons. The fact that you work so hard, pick up after your husband, fix things around the house... That's where you and I are in the same boat, and I too worry if we have a kid I'll be doing everything by myself. The reasons I'm worried about having kids though, mainly, is because of all the things going on in the world. There's so much more you need to teach kids these days than even when I was younger. I'm seeing things now that I never thought I'd see happen, and I'm only 26. I sometimes just can't fathom bringing a child into this messed up world.
I hope you and your husband work this out. Good luck! =)
Edit: to answer your question, I don't think you're obligated to have children, but I do think sitting down and talking to your husband about all this, if you had previously decided you did want children, is an obligation. Does he know how you feel?