I don't "need" to lose weight to be a model. Who are you to judge me on my appearance? You need a new outlook and attitude adjustment (and a swift kick to the groin). After the first sentence you could add in names of some models who aren't skinny, like Ashley (can't remember her last name), Amy Shumer (who isn't really a model, but has published model-like photos), if you want.

how about this "I am modeling for me not for you and your opinion of my size is irrelevant"

I would say don't dignify that narrow minded advice with a response. Whether modeling or working out, you should do it for you and your own goals not someone else's. It's sad that these days one can't try to love the way they look or even simply work out in the gym, without some unwanted "advice" or rude comments reflecting a painfully narrow opinion on beauty, etc. Keep on keeping on!