I think the maxing out after a certain number of dependents is typically only with group insurance. When we had individual coverage, we paid for each kiddo.
I get lucky at work and my medical/dental/vision is all 100% covered for me and the family.
Maybe check in with your DH's HR dept and see if it would be any cheaper or if they have that maxing out plan. I know you said it made more sense when it was just adding you and J to go individual, but maybe its not the case with the twins now? Worth a shot....