It's 2016 and I'm still not pregnant

Sharonda • Trying to ttc
I don't know what to do anymore I'm still haveing trouble getting pregnant I been trying to get ttc and get pregnant since 2010 I have three kids but I'm trying to get my fourth baby I will be 26 on the 18 of Jan and still there is no baby me and my husband been haveing sex back to back and I'm still not pregnant please help someone tell me what to do or wats wrong