S.B.
It's not easy :) I have been working exclusively from home since 2008 (part-time before that) as a paralegal and some days I want to jump off of a building! I still have 4 kids at home - 13, 12, 10 and 9, but my youngest two are special needs and are more like having a 5 and 2 yr old. During the school year, I do "OK" since they are all in school full time. Summers are killer, though. Right now, I get up two hours before they do and try to get some time in. Throughout the day, I get a few hours in here and there, and then at the end of the night, I try to get 2 more hours in if possible (sometimes I am so fried at that point, I simply can't). I do have someone come to help with my 9 yr old during the day, but she has already decided after 2 weeks, that she doesn't want to do it anymore and is planning on giving her notice. I must say it hasn't been terribly helpful anyways since I hear everything that is going on and it takes so much will power not to intervene.
If it were me, I would see if you couldn't find some morning daycare or preschool program. That way, you could drop her off in the morning (maybe she could even do lunch there) and then get a 4 hr chunk of time, pick her up and have her take her nap, which would give you another 2 hrs or so, and then you would have the rest of the afternoon and evening with your daughter.
Finally, make sure that your friends and family understand that even though you are working from home, you are still WORKING! It took my family a long time to understand, that just because I am at home, doesn't mean that it isn't a "real job" and NO I cannot watch your kid, run an errand for you, talk you through some emotional problem, etc. when I am working - I wouldn't be able to do those things if I was at an actual "office," and I cannot do them now. Sorry to vent . . . can you tell it's has been a tough two weeks since the kids have been out of school? :)
Good luck!