Why are you torturing yourself by constantly testing your boyfriend? He may have fantasies about women with a body type that is different from yours, but he has chosen you. He didn’t have to. He thinks you are sexy. He isn’t “making” you feel ugly. You are doing it to yourself by not taking him at his word that he loves you as you are.
My guess is that he has discovered that your other assets are far more important than his fantasy of the ideal body. My best advice is to enjoy your relationship with a man you describe as loving and sweet and stop comparing yourself to his fantasy image. Go back to accepting your own body and celebrate it for carrying around a heart and personality and mind that is attractive to your boyfriend.
I wish you well.