I didn't read all the responses so I am not sure if anyone has came to you with this advice, but...
I am on baby number 2 (mine will be 24 months) and although I am not in the same boat as you I have two pieces of advice.
First, my daughter as a baby always preferred me over my husband. To the point that it hurt my husbands feelings. Well I told him he needed to do more things with her. For example, I was giving her every bath, feeding her, etc. Finally when my husband started to do those things with her, especially things she really loved, like baths, she started to want both of us. So try and get your husband to do fun things with her more, like playing outside, giving her a bath, if she enjoys them. And I can say now sometimes my daughter picks him over me now.
Secondly, my dad told me, he who had three of us, that when my brother was born, my sister became very attached to him, but mostly because my mom was doing the baby things and she would need help so he would take my sister along with him. He said, it was probably because it was easier for him to watch my sister then my brother. So maybe that will help with you.
But I definately think you need to get your husband to do more things with your daughter, that will help! Good luck!