Next to nothing sex life

My husband and I have been together for 9 years and we have three kids together. We have never had that period of time where we were crazy about sex. I think the most we’ve ever had sex is MAYBE three times a week. Right now it’s probably twice a month. We’ve had discussions before because I obviously have a higher sex drive than him or at least I feel like it. He keeps telling me that all I have to do is ask for sex and he’s down as long as he isn’t tired or sick which makes sense. Well I would say that 80% of the time I ask he turns me down. It’s so frustrating and every time we talk about it nothing changes. Basically just venting because today I’m just so frustrated by it. I know sex isn’t everything in a relationship but I feel so much closer and intimate with him when we do have it that it sucks when we go so long with nothing. Anyone else have experience with this? Any suggestions? I’ve gotten to the point where I’m honestly afraid to even ask for sex because I know there’s a high chance of getting turned down. It makes me feel unattractive even though he says whenever he sees me naked it turns him on. Obviously not enough.