Trying to Conceive, any advice?

I'm 23 yrs old, my fiance and I have been trying to have a baby naturally for a little over a year. I haven't been to a doctor yet just due to having so much work, but every once in a while a depressing feeling over comes me for about a day the big "what if I can't have kids". I just get worried, but is there any advice any of you ladies might have of tricks, health tips, vitamins I should take anything would help? Thanks guys :)