Let him make the decisionAs a stepmother myself, I feel for you. When I first married DH, almost 10 years ago, I really had no ideas what I was getting myself into. Since then I had learned a lot in order to survive. My stepkids are now 21 and 18 so they are no longer my responsibility. I survived but it's not easy.
I guess the bottom line is not how willing you are to work with your SD, it's more so how willing your DP is to work with you. The two of you MUST be on the same sideline or this relationship will not work. You need to sit down and to make agreement in terms of house rules and disciplines. Better yet, write them down. Your partner needs to understand how you feel and that he respects you and your feelings. Loving his child is important to him but he also needs to remember his love to your should not come second. Believe me, if the situation doesn't improve for you, your love will gradually lose its strength in sustaining such relationship because a constant stress is stretching the trust between you and your partner.
When I first married I was naive enough to believe that things would work out as we lived together. By the time DH told me to back off and hands off disciplining his children I knew I had made a mistake. It was then too late, our marriage had produced a third child of our own. I suffered being a stepmother who was asked only to perform parental responsibility without parental rights. I resented very minute of it but I didn't want our son to have to experience what my stepchildren did so I stuck with my husband.
Now that both of my stepchildren are out of the house, my husband and I still have a lot of issues, related to all those years when my stepkids lived in the house, to deal with. Our child is the only glue that keeps us together now. Yet almost every day we both feel bitter about what we did or not for each other. This is not what I'd call a happy marriage. If you believe by putting up with the situation until she's old enough to be out of your life, I can tell you right now, the happy ending will never come. What you're going through and how your man is treating you right now will impact your relationship for many years to come.
My opinion is that if you can get your partner to agree or compromise to a level where you both feel comfortable, by all means give it a try. If you partner has his heart set on letting his daughter do whatever and whenever she's pleased, you might as well have a back up plan. A lot of time men don't understand how important it is for a woman to feel respected and appreciated. By not listening to you he is not showing you his respect, and he doesn't seem to appreciate the effort you put in trying to make the relationship to work.
Talk to him and give him a choice. You don't have to be the one to make the decision. He should be the one and you just respond accordingly. Best of luck!