Hi Emilia7,
First, a couple scriptures about having children:
Psalm 127:3-4 says "Behold, children are a heritage from The Lord, the fruit of the womb is a reward. Like arrows in the hand of the Lord, so are the children of one's youth. Happy is the man who has his quiver full of them: they will not be ashamed they meet with their enemies at the gate".
1Corr 7:14 says "For the unbelieving husband is sanctified by the wife, and the unbelieving wife is sanctified by the husband; else were your children unclean but now they are holy".
So you see, children are a blessing and deemed 'holy' by one believing parent. That's you!!!
You are concerned about your husband smoking weed. I would be too. There is too much knowledge out there on the internet superhighway to be ignorant on any matter. Do some research and see what the ramifications would be for his use. Can you convince him to agree to quit while you are trying to get pregnant? How motivated is he to have children?
You definitely raised some other important issues, just not sure if you are wanting 'advice' for those too.
Having children for the sake of having children is not a sin. Sure you would put some extra work into it since you are the practicing believer, but God is in charge, anyways. Also God can change things. I think God is a God of change. Trust me, the way things are in your life today will not be the same in one, two or especially five years down the road, LOL. You are young. Having a family is a precious gift from God that we can glean so many blessings and benefits. Don't deny yourself these because you don't see everything as being perfect. There was a time when I would see pregnant young women and think 'don't they know how evil the times are? Jesus is coming soon!' But that was almost 30 years ago and that child in his mothers womb is likely enjoying his own children now. <smile>