It takes practice.....so practice practice practice!
Same thing happen to me and my fiance. We tried last year for many months and I was late for a week. The day I was suppose to get a ultrasound and blood work I ended up having a full on blown period. Then 2 weeks after that period I got pregnant! Don't ever lose hope! I'm now 16 weeks and 4 days with a little girl !
Go to the Dr and have them run test. It took me years to get pregnant. Maybe they can give u something to help
My husband and I had two miscarriages and on our third one was the trick, we are due in 3 days. Just take your time and stay positive, it will happen for you.