Long term relationship sex decline

Just reaching out to anyone who can relate . I’ve been with the same partner for seven years the Past couple years our sex life has significantly decreased . I’m 29 and he’s 36 . He also told me within the last year that if I want to have kids he’d like to do it ASAP because he doesn’t want to be 40 with a newborn as he already has 3 kids , and I don’t have any . I’ve expressed my sexual frustration to him maybe two or three times and nothings changed . Now we’re trying to conceive and we still only have sex once a month or LESS. Am I crazy for thinking maybe he doesn’t wanna have a baby ? His sex drive being this low and me blatantly asking to have sex is getting old . I don’t know what to do because I love him and know he loves me back but he just doesn’t want to have sex . Any suggestions ?