Anyone a stepmom?

Felicia • Sometimes the greatest love of your life comes after the greatest mistake of your life. I love my boyfriend so much.
Hey girls! 
I need to vent a little bit.
I have a 8 year old son from a previous relationship and now I have a 5yr old step daughter. She is a great little girl. We get along great. We do all kinds of things together and she and my son get along and do great together as well. BUT I do have my moments with her. My BF (her dad) is over the top with her. I understand "Daddy's Girl" She is always the center of attention. Which to me is fine but to a point. She always gets what she wants. She listens and is respectful and kind but extremely high maintanance. My BF doesn't mistreat my son but he does treat him different from how she gets treated. And to some point I know its an age and gender thing but she isn't that much younger than my son to not be treated the same way. 
It has been an issue and caused conversations with my BF and I on how I "act" when she's around. He says I act different when she comes. And I know I do. I step back. To me, I do it because I don't want her to feel as if she and I have to compete for attention from my BF / her dad. Since the split with the baby momma. It has always jus been them too and for me to suddenly step in and be there all the time now, I don't want her to feel as if I'm taking him away from her. Also, I don't agree with the way she is treated. Everything is about how she feels and what she wants. If we also have my son. And or when we have nieces and nephews, it's still all about her. Attention is always kept on her. And it bugs me! Our kids have their own room, their own beds but she NEVER sleeps in her own bed. Even when we have sleepovers. All the kids are sleeping together EXECPT HER! My son sleeps in their room alone while she sleeps with us. And I can see that it bothers my son because he feels left out but I try to ensure him that I do love him and that he's a big boy and he can sleep in his own bed. There are times that I will sleep with him in his room jus so he  doesn't feel left out. I hope I'm not sounding crazy but anytime I try to say something or insinuate that she's being treated different, my becomes defensive. Especially when it comes to getting her things. She'll get 5 pairs of shoes all at once or she'll get a toy after toy or all kinds of snackable items. I understand she is his only child and she is "Daddy's Girl" but there comes a point where all the excessive things do need to slow down or stop. Our financial situation has changed and we try not to let our kids feel the change but he will spend our last dollar on her. And then here we are waiting for the next wrath of money to come. Idk if I'm making sense guys but I jus needed to get that off my chest. It really bothers me.