Sorry dear. I sorta understand how you feel. I'm the person that every complains to around here and yet when I want to talk it seems like no one has the time or they want to solve it for me. I have no problem with people saying, "well, have you tried..." but a lot of the time it's "you should go do this..." It's really frustrating.
I don't know how old your step daughter or daughter is, but it could just be the age where they pull away from parents. My mom likes to try and force her views on me, where I would just prefer she listens and maybe asks what I plan to do instead of telling me (then again, I'm 23, so it's a bit different). Also, if her and her father are closer, perhaps she feels you are just intruding into her life when you offer advice. I don't really know personally, but I've had friends that felt their step parents were overstepping or ignoring the little things only to force their views on bigger things. I don't know if this is you or not, so I could be completely off base.
As for your boyfriend, I'm assuming, I would say to try talking to him. I've had my friends all complain to me about their boyfriends, yet they don't bring it up with them. My mom will complain about something my father does, yet she doesn't talk to him about it. I don't know you so I don't know if you talk to your boyfriend or not, but generally it helps either the relationship or it helps you both decided to go your separate ways. You could also try talking to him about the step daughter as well.
If you want to do something else, I'd highly recommend writing up what is going on. Get all the details out and one paper (or a computer screen) and then reread it. Sometimes you can see things that way and solve your own issues, and then you also got it out without sharing it with those on the internet. Maybe go find a friend and tell them all this to see if they will listen to you. Just saying it can make things better.