Oh, my. This sounds very much like my situation a few months ago! When my twins were born, I felt like I had no help and that I was falling apart!!
Of course your finding this still hard to juggle. Your baby is still so tiny. Give it time.
Every woman and family is different, but I couldn't survive if I didn't get out of the house with the kids at least once a day.
Here's what helped me:
1. I found a parenting method that really worked for us (Sophie and I). It made it fun to be around her again. (It's "Love and Logic", by the way.)
2. I tell myself, "I might be giving Sophie a few months of horrible parenting while I figure out these babies, but that won't ruin her. I'll go back to being an awesome parent soon!" It's okay to yell at your family sometimes. We're not perfect. But we remind our kids that our behavior is not okay and that we will try to do better. And you will.
Okay, one more thing: DON'T tell yourself (or let anyone else tell you) that you should have things figured out by now. My babies are 10 months old and I STILL lose it with them and with Sophie. What kind of parent does that - yells at their kids? A normal parent. (Note: A normal parent does not hit or abuse their kids, though ....)
IT WILL GET EASIER.
Whether you decide to continue nursing or switch/combo with formula, you'll make it through this. It may be the hardest time of your life!