How old is too old?

I'll be 26 next month and I've never been pregnant, even though I've tried actively for about 6 months, nothing happened. Other than taking birth control in younger years l haven't prevented pregnancy and still nothing. Is it crazy for me to sit and think that my biological clock is running out and scared I've waited too late to try because it hasn't happened before now? I'm not ttc but plan to be within a year or so. We put off on alot due to career changes.