Regardless of whether you fail or succeed, the people that love you will celebrate you on your birthday. That's what its about. You've accomplished more than many in your time. I'm proud of you.
Turning 25 in less than six months (I didnt know we were the same age holy cow). I am right there with you when you mention the disappointment of not having met any goal you really had for every year back in high school. Life just doesn't turn out the way we intended for most of us. I still love birthdays. Yeah, probably in a few months I'll fall into a deeper crisis of age than I had before (I'm 25 and smart, how on earth I'm still in undergrad with teenagers?), but the day itself feels like a new beginning. Also, an excuse to indulge on eating lots of sugar and relaxing in a way that you wouldn't allow yourself on most days.