I have one bio son and three step kids.. two girls and a boy. I find that what comes naturally to me has to do with both the biological aspect and their personality and how accepting they are. Of course things are natural with my son. My stepson (7), things are becoming more and more natural all the time... I am mom in his eyes, he calls me that or M. even at times, he comes to me with things probly 50% of the time rather than his dad, etc. My youngest step daughter (10), things come VERY naturally with. She will crawl in bed with me, talk to me about anything, I've been M. for quite a while, etc. My oldest daughter (11), we only kiss on the cheaks, she will cuddle on the couch with me IF the timing is right (dad isn't around for one), but she defies me more than anyone in our house.
Another thing... their previous experience and knowledge of what a "mom" is, is totally different.
Connor was 1 when bio walked out and has come back every 6 months or so in the last 6 years, stayed for a day and left. He has never known what a mom is, or why he would need one. He's a boy, he's had dad... who needs anything else?
Taylor was 4, but bio never took care of her as an infant. What she was taught was "there's a mom in my life, but she doesn't care about me". Not to mention, she's a girl with girlie friends that have a mom... all she ever wanted was a mom so she welcomed me with open arms.
Savanah... she's a different story all together. She was 5 when bio left, and she was the favorite and the "best friend"... she was talked to as a friend, told very adult stuff, etc. I am not like that... she is my child, not my best friend. I talk to her about things that are appropriate for a 11 year old... not my friends. To her, I'm not treating her like I'm a mom, so she won't treat me like one... I'm treating her "like a baby" in her eyes.
My best advice to you is... Stop and think about what your daughter has learned from her mom.
I could go on about this subject for days but I'm sure you've read enough! Feel free to email me if you would like to chat some more though.