Hi R.,
What a tough spot for ya'll to be in!!! Have you already had the baby? Or are you in the 6 month "waiting period" until the baby is born and you can get a paternity test?
First, he is well within his right to get a paternity test and actually, he should. Because he will be financially responsible for this child for 18 years whether or not he decides to be actively involved and request parenting time or some sort of joint custodial arrangement.
As far as how you proceed - you don't really need to do anything right now except take really good care of yourself and your baby. When the baby is born you get a paternity test.
I would also look for a lawyer who has some experience in custodial arrangements and child support with parents who are not married. Because you will want to get something in writing asap.
My understanding is that you can get a DNA test before the baby is born, which you might want to consider if you think he might be more involved????
I also wouldn't hold out for him to be really involved until the baby can interact - like 2. He doesn't sound super mature and lots of guys have trouble bonding when the baby is an infant. Especially if they don't live with the mom, because you end up being the primary everything which makes it harder on him to sorta get in there and find his groove, so to speak. Not that you should move in with him for that - he may not be involved anyway.
The BEST thing you can do for your baby is to be a happy, healthy, well-adjusted mommy.
Other than that - I would just plan to be a single mom with primary custody - so do all the great things that you do before you have a baby - pick out the crib, have a baby shower, find daycare, paint the nursery.
Good Luck.