Sperm getting to where they need to be

Danica
My so has a hard time staying fully erect during sex and sometimes he ejaculates in me when he's not fully hard. I'm worried because the end of his penis isn't far enough up that it's effecting the sperm getting where they need to go. 
I've tried to google this but coming up short -.- anyone have any experience with this. I literally cried after sex today because of this (he didn't see me)