I guess the part I should have mentioned is that we've structured our lives so that we can live on one income if it ever came to that.

That doesnt mean he wants to and that doesnt mean hes happy to do that, unless hes forced to. You making nothing some months forces him into that position for those months.

He still feels that stress though for sure - he has said as much. I worry because we plan on having kids one day and both agreed I'd be a stay at home mom for at least the first couple of years. If he can't deal with one slow month for me without killing himself with stress I'm not sure how we'll be able to handle parenthood.

You will have to talk to him about this. What are his goals before children? Does he want to make a specific amount at his job first? Does he want you to have a more stable income before having kids? Is he sure that he can handle being the only person in the household with an income while you become a stay at home mom, or did his mind change and he now prefers you work part time while being a mom?

With this, I also suggest couples counseling. It sounds like you two arnt communicating very well on these topics and a couples therapist will help you both talk it through better. Theyll also be able to help you two talk out other possible compromises.