"This is the year you turn 30" and other horror stories

I had a realization the other day while driving.
I had just dropped the pup off at the groomers (his first time!), stopped off at Target to pick up some essentials for a sick boyfriend, and was on the freeway headed home.
I was going over various mundane things in my brain, none of which included actually paying attention to the road, when it hit me "this is the year you turn 30". I actually had to stop myself, and repeat the sentence I muttered off in such a  blasé manner. "This. is. the. year. you. turn. 30."
Now I've said to myself (and others... I do talk to other people, sometimes), "my 30th birthday" and "I'll be 30 this year" but those never struck me the way that sentence did. 
"This is the year you turn 30" 

That sentence holds SO much power, it is like a brick hitting me in the gut, or rather, an entire sack of bricks. I was trying to explain later in the evening to J the impact of this sentence and what it actually means. I likened it to every year you get older, there is a door that shuts out the past, what used to be, what can never happen now. Turning 30 is not just a door, it is the enormous iron (steel? metal? whatever it is) gate of a castle that slams down and locks out anyone on the other side, regardless of their status or amount of armor. It is, quite literally, the end of an era. No longer will I be able to make the claim "I'm in my 20's". Anything that happens from that point on will be referred to as happening "in my 30's". 

I'm not even sure why this rattled me so much. It is not that I am dreading my 30's, I've actually heard they're pretty great years; you still have some of the energy you had in your 20's for adventures but you're a little bit wiser about which adventures your partake in. So what is it about "this is the year you turn 30" that shook my core? 

I think it really gets down to, not so much what the 30's hold, but all that my 20's could have held, but did not. So many women my age have children, are married, buying houses, putting down roots, and are working (and by working I mean getting PAID!) in their career. Here I am, on the brink of the big 3-0 with no children, not married, renting, and working for free as a forever-student, far away from home. 

I guess I need to realize that all those things other women did in their 20's, I will likely be doing in my 30's. My 30's will not include being established in my career, they will be just beginning my career. My 30's will not be raising teenagers and preparing my kids for college, they will be giving birth for the first time (and hopefully 2nd and/or 3rd). My 30's will not be tending my roots, they will be planting them. 

When I really think about it, it feels like I'm so far behind everyone else. J says I'm being selfish when I view it that way and to look at everything I have done because I didn't choose the other path. The places I've lived, traveled, the things I've experienced and really, he is right. I want to have all of that, plus everything other women got to have in their 20's too and that is completely selfish. I want my cake; to have it out for show and have a bottomless bowl full of it. 

I am struggling with being grateful. With all that I've been able to accomplish... I'm focusing on the rest of it.Maybe my 30's will be a time to be grateful? To appreciate things a little more? 
This all reminds me of that Tim McGraw song... my next 30 years ;)