Balancing Act

For those of you that have children from previous relationships, how do you balance it all? How do you make it fair? The one fight we can't seem to get past in about the kids. I feel like things are not fair between the girls and the boys, I've felt that way for about 6 months, but every time we argue about it, he doesn't see it that way. I have felt like for the last 6 months I have had to compete with his sons when they're at our house/with us for his attention. Prior to that, even when the boys were there, he gave me all kinds of attention, but now I have to fight for my space and my time with him. He doesn't see it that way either, it's another thing we've fought about for the last few months on and off. I have suggested counseling, but he thinks that if we need counseling this early, then it's not worth it.
He thinks I don't discipline my daughters, follow-through, etc. They're out of hand and he doesn't want to see it get worse in our future. I don't see it being that bad. I think a lot of it stems from my oldest being really angry at me right now. I don't know the depth of it, but she's angry about me getting married and she's angry about the relationship she has with her dad. I have things I need to work out with her - I need to fix our relationship.
Part of our fight today is that he wants me to rebuild my relationship with his sons, but how can I do that when he and I have things to work out? Why would I work on that relationship before the one with my daughters? We pretty much have left the fight at "if you and I have issues to work out before you're interested in a relationship with the boys then we need to put a hold on marriage plans, we should have issues worked out by now". I'm really hurt and angry that he won't work on anything with me, that it's apparently ALL MY fault. I told him fine, whatever he wanted.
I so feel like throwing in the towel, it's not worth it to feel like this anymore. Maybe part of it is because the last piece I have tying me to my "old life" is going to be severed this week and I'm a little sad about that (the girls will start at their new school next week), plus I'm really bad with change.
Any advice out there?