Hi S. -- I read this a few days ago and have been meaning to write. I have a 6-month-old daughter and still feel the same way you do. I've talked to many new mom friends who also feel similarly. You are SO not alone. :)
At any given moment, I can rattle off a list of at least 6 things I need to do and don't have time for. I look at my house in disarray, my overflowing inbox, my body (hello!) and I sometimes just want to sit on the floor and cry! I just can't seem to get it all done.
I think as new moms (regardless of how many kids you may already have) we place upon ourselves an unspoken pressure to do EVERYTHING ... and to do it PERFECTLY! We must cut ourselves some slack. You do the best you can and the rest will work itself out. Right now, I often don't feel like I'm that good at many things, but one thing I AM good at is being a mom to my beautiful little girl. And that, I keep reminding myself, is the most important thing.