In Texas you are considered to be an adult at the age of seventeen. Thus, I am assuming that your case was handled by one of the adult felony courts and not one of the local juvenile courts.
If you received any type of probation you are not eligible for an expunction. Nevertheless, you are eligible for a motion for non disclosure if you received deferred adjudication. The bad news is that for a felony you typically have to wait five years after you have succesfully completed your deferred adjudication. If you your case was reduced to a misdemeanor you will be immediately eligible for a motion for non disclosure once you finish your deferred adjudication.
Your attorney should have explained all this to year before you entered into a plea agreement. Since this is a common question I have created a legal guide for people. Also, I answer this question in my blog. If you have any specific questions feel free to contact me.
This is part of the applicable section which is about sealing your record. You do not qualify for expunction The former district attorney had a form on their website. Currently the website is being revised (with a new head prosecutor in place) so they may add the form (and a summary of the rule) back to the site. Folks who wanted to file pro se (by themselves) can use it. However, it is generally better to use a lawyer argue why it is in the community's best interest (the standard), especially depending on the court.
Gov't Code § 411.081 provides:
(d) Notwithstanding any other provision of this subchapter, if a person is placed on deferred adjudication community supervision under Section 5, Article 42.12, Code of Criminal Procedure, subsequently receives a discharge and dismissal under Section 5(c), Article 42.12, and satisfies the requirements of Subsection (e), the person may petition the court that placed the defendant on deferred adjudication for an order of nondisclosure under this subsection. Except as provided by Subsection (e), a person may petition the court under this subsection regardless of whether the person has been previously placed on deferred adjudication community supervision for another offense. After notice to the state and a hearing on whether the person is entitled to file the petition and issuance of the order is in the best interest of justice, the court shall issue an order prohibiting criminal justice agencies from disclosing to the public criminal history record information related to the offense giving rise to the deferred adjudication. A criminal justice agency may disclose criminal history record information that is the subject of the order only to other criminal justice agencies, for criminal justice or regulatory licensing purposes, an agency or entity listed in Subsection (i), or the person who is the subject of the order. A person may petition the court that placed the person on deferred adjudication for an order of nondisclosure on payment of a $28 fee to the clerk of the court in addition to any other fee that generally applies to the filing of a civil petition. The payment may be made only on or after:
(1) the discharge and dismissal, if the offense for which the person was placed on deferred adjudication was a misdemeanor other than a misdemeanor described by Subdivision (2);
(2) the second anniversary of the discharge and dismissal, if the offense for which the person was placed on deferred adjudication was a misdemeanor under Chapter 20, 21, 22, 25, 42, or 46, Penal Code; or
(3) the fifth anniversary of the discharge and dismissal, if the offense for which the person was placed on deferred adjudication was a felony.
(e) A person is entitled to petition the court under Subsection (d) only if during the period of the deferred adjudication community supervision for which the order of nondisclosure is requested and during the applicable period described by Subsection (d)(1), (2), or (3), as appropriate, the person is not convicted of or placed on deferred adjudication community supervision undunder the Transportation Code punishable by fine only. A person is not entitled to petition the court under Subsection (d) if the person was placed on the deferred adjudication community supervision for or has been previously convicted or placed on any other deferred adjudication for:
(1) an offense requiring registration as a sex offender under Chapter 62, Code of Criminal Procedure;
(2) an offense under Section 20.04, Penal Code, regardless of whether the offense is a reportable conviction or adjudication for purposes of Chapter 62, Code of Criminal Procedure;
(3) an offense under Section 19.02, 19.03, 22.04, 22.041, 25.07, or 42.072, Penal Code; or
(4) any other offense involving family violence, as defined by Section 71.004, Family Code.