Position to get pregnant

Hi I am 27 and my hubby is 28. We have a 2 year old son. We are TTC but have no luck since the past 5 months. I just want to ask does the position you have sex effects your chances to get pregnant. Does your legs have to be wrapped around his waist fully open? Or can be kept flat close together? I use ovulation kits and concieve plus nothing seems to work. I am taking agnus cactus tablets. I got pregnant after 3 months when I was pregnant before. I am losing hope and want to give up now.