considering that you have known him/been dating for three itty bitty months and in the first month he was lying to you and using drugs, you barely know this guy. which means what you feel probably isn't LOVE at this point...more infatuation and romance. LOVE takes TIME.
he is just now embarking on a life long journey of recovery. if he is going to make a real go of it, he will need to keep up with meetings, with spending time with other recovering addicts and being invested in a sober lifestyle. as early in recovery as he is right now he's your basic hot mess. and will stay that way for a while.........addiction is a very deep seeded disease....it affects the person mentally, physically and emotionally. he is likely to change his mind about things many times....he WILL be moody. he will have to deal with cravings.
and none of that is the job of the girlfriend. you aren't his sober buddy. but you will have to play second fiddle to his recovery....
why not just adopt a wait and see attitude? don't cling, don't hold on too tight, and don't commit yourself to what you do not know yet.