Trying to conceive (worried it won't happen)

My fiancé & I have been trying to concieve for about 3 months now. We've done everything shy of actually checking fertility cause honestly I don't think I'm prepared to hear if one of us is sterile..... my period comes right on time every month and each time I get sadder and more worried it won't happen. I lay and cry (mainly pms) and worry that it's just not gonna happen for me, especially seeing so many women around me not even trying and having babies. Any other women out there trying to concieve with similar feelings?