Hi and welcome. I have learned the VERY HARD WAY that if in doubt - don't. There is less harm done delaying a marriage than regretting one on down the road. If I had it all to do again I would not marry until I felt absolutely 100% that I was doing the right thing. Especially with a child involved.
It sounds like your gut is trying to tell you something. I have never thought that it is a good idea to allow your head to talk you out of the doubt. If it is there - then there is a good reason for it. Whether you are picking up on what is happening or what is going to happen.
Addiction NEVER goes away. Even when people have long term sobriety they can go back out. The risks do go down but any addict in recovery will tell you that all they have is today. You will never be able to control whether someone stays sober or not so if that is an issue for you then you know what to avoid.
What is the harm in giving this more time? You have been engaged for a long time now and maybe a little longer would be a good idea.
It sounds like you are on the right track. Going to meetings and really learning what addiction is has helped me a whole lot.