Your lawyer is basically your employee. Pwede ka magpalit anytime. Kailangan lang syempre sabihin mo sa kanya para mainform din yung court so that he could be relieved of his duties before a new lawyer can enter his appearance. As to the dismissal of the case, I believe it is already being heard kasi 4 years na. Hindi naman na basta basta madidismiss yan once it is already filed in court. Presentation na ng evidence yan and it will be up to the judge to decide. Kasi nga, paano malalaman kung mahina or malakas ang evidence laban sayo kung hindi didinggin ang kaso. One more thing, hindi mo kailangang magpositive sa drug test to be charged with possession of dangerous drugs, which, i am assuming is the case filed against you. Pwede ding possession of drug paraphernalia which is another case aside from possession of the drugs. My advice to you, open up to your lawyer and discuss your case with him para maexplain niys sayo ng mabuti.