You have a right to a speedy trial under the US Constitution and the Texas Constitution. In order for this right to have any meaning, you or your lawyer have to envoke this right to the judge.
There very well may be a good reason for delaying and continuing a trial date for this long, but if there is, you are entitled to know why your lawyer is doing this. If you want to just proceed to trial, then you need to let him or her know and demand that they respect your right to a speedy trial.
Disclaimer: This answer is provided as a public service and as a general response to a general question, it is not meant, and should not be relied upon as specific legal advice, nor does it create an attorney-client relationship.
In addition to Mr. Walcutt's information, as long as the case is put off, you have not been found guilty. If you were/are guilty, then if you have demonstrated "good behavior" and that you do not have a drug problem any longer (if you did), then it is more likely the case will be dismissed.
If you want the case to be finished (which I can understand, especially if you are not guilty), tell your lawyer that you would like to have your case heard. He can demand a "speedy trial" on your behalf. The right to a speedy trial does not really begin to run until it is demanded by an accused (although there are other issues which may be raised after a long delay.)