Done having kids?

we have 2 kids, age 4 and 2 and are working on our marriage but after having read a lot of this site, I'm thinking that hope for a normal life is pretty much off the table. I really want another child but I feel like I would be choosing between having another child or preserving my marriage. Even if we are done having kids, there still aren't any guarantees , but I feel like having a third would put a lot of stress on me and our marriage and isn't worth it. It's a sad realization, actually. DH is on add meds and has been for years but still suffers many of the symptoms related to it. We just ordered the couples counseling from the site and I'm hoping it helps. Thoughts?  DH made it clear when we married that he only wanted 2 kids. He certainly hasn't changed his mind