Stop thinking that way. I didn't get married until I was 38, and had my first kid at 44 & my second a month before my 48th. I still stomp on all those 20 something dads. OK, I work out a lot so I can keep up with the boys as they grow. But there are pros & cons to later parenthood, but that is the least of your concern right now.
Don't try to predict your future. Nobody gets it right. And certainly don't make yourself miserable about it, you've got enough right now to be miserable about
Me: 50 W:43 S6, S3 M: 12 yrs. T: 17 M is bad & Not happy Bomb Mar '14 S 5 Feb '15 D Bomb 13 Apr '15 (but "no hurry") DB Coach May '15 Wants proceed on D Aug '15 Starting 1-on-1 negotiations Sept '15