Fertility

Me and my husband aren't fully trying but we've had some mishaps and I feel I should have gotten pregnant by now... and nothing has happened. I'm currently 28 days late according to my <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">period tracker</a>. I took and test and negative. Should I be worried that I cant have kids, also how do I go about finding answers!?!? Help please anything helps.