Why is it so hard to get pregnant???

Amber • Hey my name is amber & my husbands is eddie. We have 1 child who is almost 7 yrs old we`ve been trying for 5 going on 6 yrs to have another.
We been trying for 5 yrs. We have an a almost 7 yr old. Everyone says don't think bout it or it'll come when God wants it too well God also said 'TO BE FRUITFUL & MULTIPLE' DOESNT THAT MEAN. HAVE CHILDREN AS OFTEN AS U CAN??? WHY IS IT SO HARD? MY HUSBAND IS 37& IM 26. I JUST FEEL BUMMED ANY HELP OR ADVICE ANYONE???