I don't see any reason to get a lawyer now, to be honest. You've already done his job (and done it pretty poorly, to tell you the truth).

You're first mistake was admitting use. They could not have charged you all with possession without your admission. You have to be in the same room as the pot to get charged with constructive possession. You should never admit anything to the police. Leave that to your lawyer. That's what you pay him for. He could have pled down from possession to use as easily as you did (even easier actually), and, what's more, he had a good chance of getting the charges against you dropped... except you talked. Never talk to the cops except for your name, address, drivers license... that sort of identification stuff. *Never*. They try to tell you that they'll go easier on you if you talk, but that is always a lie. The only way they could've gotten you for anything is with your admission... and they knew that.

I believe they could have searched the room anyway given that odor is usually enough for probable cause to search. So letting them do that was probably not a huge mistake. In fact, it could have helped them to not tear the place up too much and find more bud, since they felt you were being honest. I believe sometimes consent to search is a good thing to give if you think they probably will get probable cause to search anyway. This is especially true if your weed is extremely well hidden and you don't want dogs running around.

However, most of the time I advice to not consent to a search. And never, ever, ever talk or admit anything to the police. Leave that to your lawyer.