Bf always guilt tripping me because our sex life is “dead” and it really hurts my feelings

So my bf and I have been together since we were like 15 and 16, I’m now 21 and he’s 20. We have a 2 year old and I’m currently pregnant again after having a miscarriage last year. We don’t have sex a whole lot anymore, we do sometimes but most of the time I’m too tired from parenting a toddler all day on top of pregnancy nausea, fatigue, etc. he’s always pestering me for sex but I’m never in the mood due to like a million different things. My body count is higher than his so he always says that im just “tired” of sex because I’ve had more sex than him and that I “got my f*cking days out but he didn’t” and that it’s not fair he’s only 20 and never has sex. I’ve tried and tried to explain to him why I’m never in the mood but he doesn’t get it or just doesn’t care. The constant pestering about it and him “expecting” it from me just because we’re together is another thing that makes me not want to do it. I wish he was more understanding. Like MY body changed, not his. He’s still the same person he was before we had kids but I’m completely different. All in the past 2 years I’ve been pregnant 3 times, I’ve had a c section so I have a huge scar and not been able to lose the belly weight “mom pooch”, I’ve went through a miscarriage, I’ve been on birth control that ruined my body, I’ve gained a ton of weight so I’m very self conscious, I have so many stretch marks that I never use to have, I have PCOS, depression and struggle with mental health in general, I’m a full time stay at home mom WHILE pregnant so I’m always exhausted at the end of the day and “touched” out from my toddler, it’s like none of that matters and he’s the victim because he doesn’t get any p*ssy. It really hurts my feelings because I feel like he can’t just be happy with me WITHOUT being sexual all the time. We go back and forth about this a lot but this is just one example of a conversation we just had about us never having sex anymore.

EDIT- this was his response to my message. Usually when I tell him why I have no sex drive he just ends the conversation. He edited and deleted 2 messages before I could finish reading them but he basically said that at least we still have “plenty of time to act like old people and “knit sweaters” together if we’re not gonna have sex with each other” I guess I took to long to respond so he didn’t wanna talk about it anymore.