If you go to court and get an order signed by a judge, you will receive specific rights and duties as a parent.
See Section 153.072 - Section 153.076
You will need an attorney to explain rights and duties.
You want to fight for the rights and duties to either be(1) independent or (2) joint.
I'm sure the other parent wants them to be exclusive to them only since that means that they don't have to consult with you before taking actions regarding the child.
You need a competent family law attorney to represent you in court.
I have seen one parent have "sole managing conservatorship" but both parents have independent rights or the other parent has the right to make decisions. The rights and duties can actually make "sole managing conservatorship" a hallow victory.
Right & duties over a minor child are vital to co-parenting.
Don't ignore these essential elements of parenting.
If there are no court orders regarding the child and you are not married, then odds are that you are legally a "stranger" to the child. Merely being on the birth certificate is not enough.
Get before a judge and get an order signed stating that you are a legally recognized parent to this child, that you have visitation rights clearly set out and that you have rights to make decisions regarding this child.
Don't wait do it now!