Jessica,
You didn't mention how old your ex-boyfriend is but he sounds very young and immature. If you believe he'll be a good influence on your daughter you need to have an honest conversation with him about his relationship with you and your expectations of him as a contributing parent to raising your daughter. And until he commits to having a committed relationship with you as a parent he shouldn't be allowed to "make all the decisions" - his decisions right now should be about how to be a good father which should include how to help support you during your pregnancy and how to support you and baby once your daughter is born. Determining her name and telling you not to date aren't as critical as getting you to doctors appointments, preparing you for labor, making sure your baby has a nursery set up in your home, making sure you have health insurance, and making sure you have a support team once you and baby come home.
If you believe he's ready to run if you ask him about his committment to the baby you need to have the conversation NOW so you can make plans without him.
Good Luck!