No climax No orgasms

Never once have I had a climax or orgasm during sex with my DH, we've been married for 3+ years & we've been TTC for the last 6 months but no luck. Once when we had a huge fight and I mentioned about not feeling anything down there when having sex & he got upset so I made up that I said so because I was angry (but it was the truth). Now that we've been TTC for months now, I'm concerned if it is the reason why we haven't been able to conceive. I'm getting very worried, although I told my OBGYN about it, I haven't been able to tell him because I don't want to hurt him. Every time when we BD, I don't get even close to getting done & I have to pretty much fake and lie to him that I got done too. In fact, I get done after he goes to the bathroom, that's when I masturbate & make myself feel better. I have never had issues like this with my ex, always had great sex and no need for masturbations. At first I thought it was probably because of the size of DH's penis, because it is certainly the smallest I have ever seen in adult (may be 4 inches when erect). So I thought even if he gets erected it still couldnt touch the parts where it's suppose to touch inside me down there. Couple of times, I even watched porn right before I BD with DH which helped a little for me to get all steamy but again no orgasm & climax was no where close. What should I do? Any one in similar situation? Can I still conceive like everyone else under this circumstance? Please help!!!!!