Hi Wyric,
It's a nice surprise that you decided to post back, addressing certain points made by different PC members. This post being your first, I felt worried that we may have scared you away by sharing our different perspectives of the situation with you!
How long has your gf been divorced? Does she have full-custody of her daughter, or is custody split with her ex? How long have you been with your gf/fiance?
I can't recall if you two are engaged, for some reason I'm thinking that you are. Personally, I would be wary of making a major commitment at this time in your lives. Imo, you need to spend more time together as a couple and some time as a family too. It takes time for children to adjust to the changes in their world. I think that your relationship should be taken slowly, to create a strong sense of stability and trust. That is my personal belief.
You two should also be sure to discuss your beliefs in raising children. What is/isn't acceptable; your parenting styles; acceptable foods, drinks, sleep times & limits; do the both of you want more children? If so, how soon?
Children really complicate romantic relationships. Many couples break apart after having kids, because they never really worked through issues that can pop up as a parent/caregiver. Our children demand all of our time and energy, but we have to figure out other ways to include our love in our daily lives at the same time. NOT an easy task ~ but it is very important!
Best wishes to you and your gf. Hope that her daughter is doing well