would it be legal since neither I or she filed for child custody in texas after our sons birth to have him live with me in Wa.

We lived together, had a son, we didn't work out. left to go into navy, now live in WA. He is 8yrs old .Neither she nor I ever filed for child custody, their is nothing filed. I do pay child support. He wants to come with me. Do I file for custody in order for this to happen? My son lives in San Antonio Tx. What can I do???