Between a Rock and a Bigger Rock

Remember that Talking Heads song "Once in a Lifetime?"  The one with the line, "You may ask yourself, well, 'how did I get here?'"  That's how I felt today.  Okay, to be perfectly honest, that is how I've felt for a long time - like, for the last year.  But today, for no reason I can put my finger on, it really hit me.
How did I get here?  When did I make the leap from bubbly, happy, and hyper to bitter, miserable, and perpetually exhausted?  And how do I un-leap?
I remember having a discussion with Husband right after I graduated from college and got my first "real" job.  We were talking about having kids and I told him I would get a job making big bucks and travel the world and he could stay at home.  I would come home a couple of times a year, have a baby every couple of years, and he could be Mr. Mom.  At the time, that sounded like the perfect arrangement.
But oh, how times changed.
Now all I want is to be able to enjoy (and by enjoy, I mean spend as much time as possible) with Husband and Progeny.  I want to be able to provide for them without living most of my waking hours in Strokeville.  I want to be able to cope without enough meds to keep a horse chill.  I want to NEVER have to miss one of Progeny's school functions or field trips.  I want to always be the one who stays home and comforts and cares for him when he is sick.  I want to leave my desk every evening feeling good about what I'm getting paid to do instead of feeling empty.  I want to be the kind of person who gives 100% of herself to her child and her husband - not the one who gives them whatever is left of herself at the end of an endless string of worst days ever.
This past weekend, I looked at Progeny and realized, the days of him being so sweet and cuddly are almost over.  And I feel like I've missed it all.  I've missed the most precious years of my one and only child's life.  And for what?  He's not the least bit impressed by his mom's job.  All he knows is, Mom works all the time.
I just feel like I've gotten it all wrong.  And I don't know if or how I can make it right.