You will definitely find many good tutoring services in a big city like Houston by simply Googling. Most top tutoring companies like
Manhattan Prep and veritas prep also have centers there. You can pick a tutoring service based on your budget. Try to read reviews on google and yelp before signing up. Avoid reviews on here.
Also, you could try studying by yourself by either getting books like manhattan's All the Gmat series or Veritas book set. Or you can sign up for an online course like TTP. Try out the trial versions of the online courses, before you sign up for any.
Since you have limited time, I would suggest take a mock and analyze your weak areas before you move ahead.