All I can do is share my personal experience and where the Lord has led me to this point. To be honest smoking weed in and of itself I do not feel is a sin. That said I started at 15 and smoked every dang day of my life up to a few years ago. I don't feel that a person that can maybe smoke every now and then, like on special occasions or something is really sinful, but the way I smoked, from dawn to dusk everyday, is nothing but a sin. I know myself and know that I can't handle it any other way, I just can't do it every now and then.
Even more than that, and the bigger issue to me personally, is the fact it could make a brother struggle, and hurt my testimony. I don't know what I'd do if I was being used by God to help inform a lost soul, they were really listening and letting it in, and then find out I smoke weed and throw there hands up declaring they want nothing to do with hypocritical Christians. That to me is the much more dangerous problem with it.
I actually smoked as a truly reborn, Spirit filled, regenerated Christian, I was saved no question. One day I was praying and honestly bringing the issue to His feet and I feel He told me "If you really want me to use you then it's time to put it down, I will still love you if you don't, and you can stay in your nice safe weed routine, but if you truly want to do the things I've called you to do then you're going to have to leave this in the past." Well by His power and Spirit I removed everything from my house and car and chose that day who I was going to serve. Within a week I was called and things happened where I now go up to the jailhouse to share truth with the inmates, I mean God leaves NO room for doubt in these matters. That is the way and how I've come to see it.
My biggest "advice" for you is to just keep the line of communication between yourself and Him open and don't just rely on others opinions in these matters. Don't get me wrong bringing it here to get different perspectives is awesome and a BIG part of it, but some will tell you that your not even saved if you are still smoking, and others will say that there is nothing wrong at all with it. That's the amazing beauty of our God, He came down to bridge the gap between Himself and us so we can keep in contact with Him through all these matters, and that's what really matters is that you go to Him when struggling or wondering about these matters. Thank you so much for being brave enough to ask and be honest with us here, and I pray in Jesus name that He lead you to exactly where you need to be. We love you sister.