Gain weight

I’m 17 My name is Kemly , I use to be healthy and eat regularly now I don’t. Its not that I don’t want to eat because I do.! Like I LOVE FOOD girls let me tell you..

But I live with my boyfriend now and his family doesn’t buy or cook food. So I don’t eat healthy or as much as I’m supposed to. Can anyone help me gain weight because I’m losing a lot of weight. I’m 94 llb now , my height is 5”0. I use to weigh 115 llb. I quit my job and got a new job now so I will be able to buy groceries again , but I would love to know how to gain weight in other ways as well. Please help Thank you !