me and my fiance are wondering how we can split custody were still together we just wan equal custody over her.

You can file a paternity action and agreement stating that you are agreeing to joint custody.  Another approach is that you can sign a paternity affidavit and there is a portion where the parents can agree to a joint custody situation.  Finally, I noticed that you said you and your fiance were wondering.  Once you are married you will both share joint custody over your child as a married couple.