Feeling like I need kids soon.

I'm only 21, but I have lupus and other autoimmune disease/conditions. We probably could afford kids pretty easily if it weren't for some times when we would need to be off of work (maternity/paternity time and at the end of my husbands education (6+ months) when he will be student teaching and will not be able to work. Somebody talk me down or assure me? As of right now we live very well (not excluding wants such as Netflix/Hulu and still having regular date nights) off of 1700 a month and can save $600 a month (by conservative standards, not including tips and such). With my job I get a discount on childcare so that it's only $400 a month. This would also be the first grandchild/great grandchild in a very loving and giving family. Anyway, this may be a better description:
We will be able to afford so much more once my husband gets in his career rather than just working where he can work (where he's already gotten 2 raises and is assistant manager and it's only 8 months into him working there). I'm just so worried about it taking forever/having multiple miscarriages (I already had one over 2 years ago when we were unexpectantly pregnant.) So many get unexpectantly pregnant and are able to make it work, and I feel if they can, we definitely could with where we are financially right now. I just feel like with the added pressure of my health condition it's harder to think straight with my anxiety of he possibility of waiting too long until it's too late.