Hello Autumn! Welcome to the forum.
There are all kinds of configurations around here and different stories about why various partners are in this world. I think you will find kindred spirits.
What does your partner think about poly for herself? Depending upon where she falls on the asexuality spectrum, there could be a lot of unexpected variables in play since this is all so new to you guys. Does she yet know how she is going to feel about your potentially having all of the tender romantic things you two share with someone else plus the added element of sex with that person?
Sounds like you're taking a slow, thoughtful approach.