I Need Advice! PLEASE!!

My husband and I have been together 11 years, married 3 on Nov. 7. I've never felt insecure in our relationship, I've never felt the need to go through his phone or anything like that. I've just always trusted him 100%. I also know that he watches porn sometime and it has never bugged me at all. Well I'm currently 34 weeks pregnant with our 2nd son and for the past couple months I've just been feeling super insecure, I go through his phone at least once a day.. I've never found anything might I add. I always just feel he's going to cheat on me or something. Well tonight I went and laid in our bed and he went to the living room I was laying there and something just told me to go see what he's doing.. so I sneak out of bed quietly and stand at the door for a minute.. when I turn into the hallway he's laying on the couch and I see him like immediately put his phone down and like pull his leg up, I knew what he was doing right then and there.. he was watching porn. Like I said before it has never bugged me in the past but it just bugged me sooooo bad tonight like it just really made me angry! So I just start asking him if he's just not attracted to me or just not happy with our sex life.. and at first he just said no that not it, idk why this is bugging you so bad you know I do it. And he's right idk why?.. but finally I just push at him some more and he tells me he's not happy with our sex life.. and it just immediately made me so upset.. but I can't blame him because it's not the best. But just hearing him say it just hurt my heart so bad! So I asked him was it quantity or quality that he's unhappy with and he said quantity.. we have sex like once a week if that.. and he said I never the one to start it it always has to be him. I can't help but think is it only porn he's watching.. or is there other things I don't know about? I HATE feeling so insecure! I've never experienced this! What should I do?