Simple answer, you need to hire an attorney. DHS and youth court are complicated entities that have separate rules that sometimes they themselves are hard pressed to either explain or follow. You most likely need to bring an action in chancery court to resolve the matter. You can attempt to do this yourself, however it is extremely complicated and you will be held to the same standard as an attorney.
Many on this site, such as myself, practice in chancery court
The law office of Anders Ferrington 601-316-8428 practices state wide. In no way am I offering you legal advice, and in no way has my comment created an attorney-client relationship. You are not to rely upon my note above in any way, but instead need to sit down with counsel and share all relevant facts before receiving fully-informed legal advice.
If the last court order that was entered gives custody to your mother, then she will continue to have custody until another order is entered granting you custody.
You need a lawyer now.
No attorney-client relationship has been formed by this answer. The answer given herein should not be your only inquiry into the matter or issue. You should schedule an appointment and seek the advice of an attorney to fully explain the facts so that the attorney can make an informed analysis and recommendation concerning your problem and advise you of all of your rights.
Sign up to receive a 5-part series of useful information and advice about child custody law.