Yes, we all feel overwhelmed at times, I think. I think that, over time, you'll learn to manage to juggle all the balls in the air that you NEED to juggle..
and learn to set down those that aren't so important. These are just generalities, and may not apply to you, but for example:
some folks think they have to have an immaculate house, and get overwhelmed when they just don't have the energy to clean every day like they used to. Well, y'know? dust bunnies never choked anyone. Sometimes it really IS OK to just not vacuum every day. Or make the bed, complete with comforter, bedspread, dustruffles, and all those fancy pillows. Or wash the kitchen floor EVERY day (like, I know there's the expression, "my floor's so clean you could EAT off it!!" When's the last time you served dinner off the floor???)
I don't know your schedule, so can't help you figure out what maybe you don't NEED to do, vs. what should be done regularly. I can tell you this, though: your daughter will be much more grateful about your attempts to care for the kitten than she might notice that her laundry isn't done. Or that her bureau is dusty. (And besides...how old is your daughter? never too young to learn how to do some stuff for herself..and to help you!!)
As for the Avonex. I've never found advil or aspirin to do much to touch the side effects from the interferons. I know they tell you to take advil or tylenol; you might try ibuprofen (you can get it generically, pretty inexpensively, at most pharmacies) and see if that doesn't work better for you.
...I am not a doctor, nor health professional, and don't pretend to be one, here.....