I'm Old

My birthday is Monday...my 31st birthday to be exact.  I'm a big fan of my birthday and certainly not one to ever wallow at my age...I mean, I'm pretty grateful to still be here and have all that I have, so what's there to be sad about?
But if there was ever a year that was a bit hard to swallow, it seems to be 31.  30 was a little hard too to be honest, but it was a big decade birthday, so it was exciting.  This year I'm officially in my 30's, like not just 30, full fledge into the decade...seriously, am I really that old?
Plus, all around me there has been some pretty scary evidence that I may not be as young as I would like to think that I am:

• a radio station repeatedly "takes it back old school" to 2003....THE YEAR I GRADUATED FROM COLLEGE...not even high school, college...how is that old school?
• when looking for a new car recently, people repeatedly suggested a mini van for us...after repeatedly replying that I am too young for a mini van, I kind of had to come to terms with the fact that I am actually the mini van's target driver (no, we didn't take the plunge though...still holding on to my SUV!)
• I am no prude and actually quite liberal, BUT I have been a little horrified at some of the content on tv (namely, MTV like "Jersey Shore" or that show about pants or something) that is broadcast right in the middle of the day...it's one thing to show it after 10PM when younger kids should be in bed, but all that language/sex during the day...yikes!
• my back hurts, presumably from lifting both boys as much as I have to, but still, only old people have backs that aches
• when ordering drinks or purchasing wine, no one asks for my id...and when they do, I'm taken aback by it

Again, I'm not necessarily complaining, just in a bit of shock that I'm going to be 31!  Anybody else perpetually feel like they're not possibly old enough to be the age they are?  I mean, really, shouldn't I just be graduating high school or something?!?