I feel like my fiance has very low sex drive

Hi ladies! I've been meaning to vent about my thoughts a bit. My fiance and I have been together for over 2 years. We are engaged, have been trying for a baby for over a year with no luck. When I say 'trying', I don't mean honestly trying the hardest we could. I'm the type of girl who would love to have sex everyday, multiple times a day if I could! My fiance however, doesn't seem to EVER want sex. If I don't bother to instigate sex, he won't instigate it to me for atleast 4-5 days, even longer sometimes. And this isnt super mind blowing sex that hes been holding up in him for days, its just meh kind of sex. 🤔 Also, when I instigate sex, he very often acts like it's a chore, That he doesn't want to or just flat out act annoyed that I want to. Could call it a dry spell, but it's been like this for a very long time. I love him while heartedly and I wouldn't break up or cheat all because of this issue, but I do get very self conscious or wonder what's wrong with me or him as to why we don't have sex very often. We are in our 20s, sex should come naturally. I feel like maybe the reason why doesn't have sex drive is because he has low testosterone, or sperm count, and why we can't seem to get pregnant? Stress doesn't seem to be the issue as this is ALL THE TIME. I feel like it has to be something in his body that doesn't want sex. Talk your thoughts out with me!!