Modification of Custody: Can the Other Parent Take Custody from Me

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

ok so long back story but i think its important father lives in illinois me in texas. he pays no child support has not court order visitation and isnt even on her birth certificate she has my last name not his. i had gotten word that he was thinking about taking custody from me because he wants all his kids together living in illinois ( two older and one younger then the one we have) he had custody of his two older kids because the mom gave them to him he did not win any kind of custody battle he gave custody to his parents so he no longer does and he has no custody of his youngest kid. now im currently in school full time (only have 10 more weeks left) and im not working that was a agreement with me and my parents as long as im in school i don't need to work they would help me as much as needed. now i dont plan on taking him for child support ill let him see her when ever he wants but he never ask to never ask for pictures or how shes doing. but if he really plans on getting me for custody could he win since i have no job and cant prove i can support her at this time. he is not a fit dad i can prove that he lives with his parents and cant support the other three kids he has the house is unfit for kids to be in i lives there for a little bit while pregnant im just really worried now after hearing her was thinking of taking custody from me im sure it wouldn't be any time soon if he really is and i hopefully will be working the job im going to school for but is there any chance he would win and take my baby away from me?