Almost thirty!

So I turn 30 in two days.  I am excited for the party J is throwing me on Friday and enjoying a day off hanging with my parents....but I must say turning 30 and still not being 100% sure I'm ready to get married to this man is making me anxious.  My life is slowly drifting by with no big changes, while almost all my friends now are getting married or having kids (after getting married!).  It depresses me.  What if I can't get to a place where I'm ready to say "I do" to J?  Then it is time to start over...and I'm so old.  I know logically I still have plenty of time....but tell that to my biological clock!