I think there are many factors to consider. What is your dh going to study? What are the job prospects and typical starting salaries in that field? If it isn't enough to support you and a few kids on, then you are going to be in a tough spot. You also are living rent free now. That's typically one's biggest expense, so while you might be OK on $20k/year now, with no kids and no rent, it might be very different if you had to pay for housing and support kids.
Now, I'm not a SAHM, so my perspective is different, but I would never, ever put myself in a position where I had kids and couldn't support myself and the kids. Marriages fail, people leave, people die, etc. While we wouldn't have the same standard of living without both our incomes, I could support the kids if I had to. That is very important to my peace of mind.
I work in higher ed. I wouldn't take out loans for going to college if it weren't to study something that would lead to decent employment. You can, however, study some things that lead to an associate's degree and reasonable starting salaries, that I think are well worth it. Many of the allied health fields, for example, make reasonable money with an AA.
I don't know anyone who has made any appreciable money selling crafts as a WOHM. I do know many women who do it, but it doesn't bring in much at all. Very few people are willing to pay enough for crafts or handmade products to make it a going proposition for most folks.