This is a really strange case when you look at the Texas statutes.
Under Section 101.003 of the Family Code, you are a minor if you are under 18yrs. of age.
Under Section 261.001(1)(K)(4)(b)(iii) of the Family Code, neglect is defined as, "The failure to provide a child; food, clothing, or shelter necessary to sustain the life or health of the child..."
Under Section 22.041 of the Penal Code, defines the crime of abandonment or endangerment as being applicable to a child
15 years of age.
It would seem that your mother could kick you out and not commit a crime, only a violation of the Family Code, which means her parental rights could possibly be removed. 8)
Minors, generally, cannot enter into contracts. However, there are exceptions in the case of the minor contracting for a "necessity" or to purchase something of little value, such as a candy bar.
Assuming housing is considered a "necessity" in Texas; your leasing agreement with your mother is valid and enforceable. Eviction notices must be given on at least a 30 day written notice. In some states, the 30 days would fall at the end of the next month past 30 days. E.G., 30 notice given on Jan. 15th, would carry over to Feb. 28 (unless it is leap year), not Feb. 15th.
Good luck dude.