Sex while pregnant

I'll give you some history first.... I've had two miscarriages one at 8wks and one at 7wks, I'm currently pregnant with our rainbow baby and I'm 14wks 3days. Last night was the first time I have felt ready to have sex with my so, but I'm petrified I know it's completely natural and it won't harm the baby, but I am so scared that I am going to lose this baby that everything scares me! My partner is also very well endowed down there and our normal sex life is very rough and we don't really make love it's the way we have always been we are both very passionate people. Are there certain positions that are better during pregnancy? Or any help to help calm my nerves would be appreciated. I just don't want to do anything to harm this baby or put my pregnancy at risk.