Attatchment issues - what do I do?

My four month old daughter wont sleep during the day - ever. Apart from the fact that I'm concerned about her not getting enough hours of sleep in total (she sleeps well at night) it is utterly exhausting because she wont be by herself without screaming and crying. She wont even sit in the bouncer beside me (for even less than a minute!), I have to be holding her, and more often than not walking aswell. I've got no help in the day and it's getting to be too much, I cant get any thing done. She will sleep for short bursts while I'm holding her, but wakes very upset when I try to put her down. I feel like I've tried everything. Is there something I'm doin worong or should be doing? Why does she hate being by herself so much? What should I do?