My question involves a child custody case from the State of: Texas

I am a non-custodial parent of a 5 year old girl. I have no felonies or a history of family violence. I have been paying child support for 4 years now, and I am ahead on these payments. I've been gainfully employed since becoming an adult. My daughter lives with her mother, which also has no felonies (that I know of).
My daughter's mother has had a case with Child Protective Services in which all 3 of her children were removed from the home. The reason why the children were removed was due to her extreme alcoholism. My daughter was given to me while her mother completed a rehabilitation program. I had a good relationship with the CPS officer and she told me that she would help me with getting custody of my daughter. It was later explained to me that they were not trying to split of the mother's family and that they needed her to get herself better so the children could go back to her. I gave the mother another chance to do right by her children and didn't pursue custody at that time. Her mother then entered a program for single mothers that provided housing and childcare while the mother went to school to further their careers or better their lives. She had to move 250 miles away and a new order was agreed upon where I would get visitation once every month and 6 weeks during the summer. (I think it was a pretty standard order) -- So, the mother called me 5 months after being at this program and tells me that she didn't like it where she was and was coming back to Dallas. When she got back to Dallas, she got a job, a home, and overall seemed like she was finally getting on the right track with life.

About a month ago things started changing. I couldn't reach her on the phone, couldn't get my daughter on my weekends, and most of the time wasn't home. I chalked it up as her working all the time. When I finally reached her, she asked me to pick up my daughter from her grandmother's house. I asked what happened to my daughter. I was told that her mother had started drinking again and she couldn't see her while she was drunk. This is a 5 year old girl telling me this. Apparently, there was an issue where the police were called because she was drunk and was fighting with her oldest daughter. This is not the first time the police have been involved in a situation with her while she was drunk and violent.

I'm torn because her older children will end up in foster care if they are taken away from her again, and they are very good kids and don't deserve that. I don't want to get CPS involved, again (I promised my daughter I wouldn't if she told me the truth about what was going on and I don't want to lie to her), but I don't want my little girl to be put back into a volatile situation where her well-being is threatened. I need to get custody, need to know if her instability and track record justifies the court to remove my daughter and give me custody whether it be primary or full, and how I can go about getting the ball rolling the fastest way possible. She needs a normal upbringing and deserves it.

Any advice or direction would be greatly appreciated. I don't have a lot of money, but I can always make payments, so if you know of any legal counsel that will work with me, please let me know.

Thank you.