@swuaveg,
Go back to your mother and try again. Be respectful (of course). You want your baby to either know her grandfather or at least know her genetic history. There is a health angle to all of this.
Hopefully, your mother will say more to you.
You can also check your birth certificate. And talk to people who knew your mother at the time of your conception. That is, her siblings (if any), long-term friends, your grandparents if they're still alive, etc. Ask who your mother hung out with or dated.
Don't be surprised if people don't say much, or don't remember much (after all, it's been over a quarter of a century). Don't be surprised if this upsets your mother. Furthermore, don't be shocked if your biological father is dead or in jail, or was married when you were conceived, or was an abuser or even a rapist. Those are often the reasons why nothing is said to someone in your position. I'm sorry, but that is often what happens.
You can also check ancestry.com to at least see if you are mentioned there, but I wouldn't hold my breath regarding seeing information about your biological father there.
Best of luck to you.