I feel bad

I want to send my bf sexy/nude pictures but my body type is not what he likes. I do not have an ass never did and he likes the really big ones so it’s like he always lets me know my ass is flat . I’m not the smallest person but I have lost weight since I had my son 3 months ago so I just feel bad. He keeps saying if I gain anymore weight he will get rid of me Idk if he is joking or not but it still hurts. My thing is he likes women bigger than me but if I get bigger it’s an issue. Im just venting because he wouldn’t understand if I brought it to his attention.