Why is an adjournment in contemplation of dismissal still on my record after two years?

An adjournment in contemplation of dismissal (ACD) is not the end of the case. You have to actually file the needed paperwork in order to dismiss the case. It's likely still on the books as a pending criminal case.

You need to get a lawyer (perhaps a different lawyer) to go back and clean this up. You should also look into the laws in your jurisdiction and see if employers are allowed to consider arrests not resulting in convictions in their hiring decisions. Some state laws only allow employers to consider actual convictions.

Some states also allow dismissed or expunged crimes to be reported to governmental employers, whereas private employers would have been told that there was no record. It depends on how the statutes are written in your state. This is why you would be best served by consulting with an attorney experienced in drug cases and expungement of a criminal record.