lingerie help

so the guy I'm with wants to buy my lingerie and he always says how much he loves my body but I just hate myself. some days I'm not confident at all and other days I can strut around in my panties and feel so confident! I want to try new things and be comfortable around him but I don't know what to do. I'm not 100lbs and I don't have a thigh gap, so I think that's why I have such low self esteem, because society deems beautiful as a size 2 with a thigh gap and D cup boobs.