Oh, you deserve a huge hug!
Let's just say I'm about six years ahead of you. Six years ago, I could have written this post. We were in exactly the same position.
The fact that I'm writing it from the UK says a great deal.
The baby is a game changer. If you have a close-knit family who is going to want to be a part of the baby's life and you want your baby to have the kind of life you had as a child, AND you both know beyond a doubt that you can both get good jobs, with excellent insurance and live in an area you love - then go back to the US. It sounds like you're leaning that way and from my expatriate parenting position, I wholeheartedly agree.
We bounced back and forth a lot from 2005 to 2007; two years ago our son was born in the US, we lived there until this past summer when a $1,200 bill for routine vaccinations (and we were well-insured!) put the nail in the coffin on that venture. We had more than a few issues with health insurance along the way -- paying more than our rent to keep our policy while we were between jobs, being underinsured when DH broke his ankle and not being able to afford the $20k to fix it, arguing about coverage -- and it really, really disturbed DH. We have had good insurance, great insurance, terrible insurance and -- frighteningly -- no insurance at times and really, the whole thing just became a deal-breaker for us (along with sky-high property taxes and rampant political conservatism that scares the life out of us at times!). So we moved back to the UK this summer with some regrets, but largely a sigh of relief.
My husband now has US citizenship, so we no longer have to go through hoops should we ever decide to go back -- an option not off of the table and an idea that I'm sure will come up more frequently as my parents get older -- but for now, the UK is the place we need to be. I'm pleased with my son's early years education progress, I love all of the local activities available to us as a family, we're exponentially healthier. Yes, we sacrificed having our "big" house in the US; yes, I miss my close-knit, huge family immensely, but DH enjoys his job in London far more than he ever enjoyed his jobs in the US so for us, the decision was made based on what was best for the three of us. And seeing as DS and I are back in the US for a few weeks roughly every other month, we're not missing out on much -- we're there for birthdays, holidays, etc., so I don't feel that DS is missing out entirely. For us, this works.
But if I had all of these things -- a job DH loved, an area we loved to live in (I love my family but I grew up in a fairly rural location that drives my city-bred DH bonkers!) and proximity to family -- in the US, then it would be no contest. The US would win, every time.