Food

So I am 19 years old and was never taught how to cook. Sadly I have a really bad eating style due to being autistic and lots of foods disgusting to me. Though I really need to know how to cook. I’m not gaining any weight funnily even though I eat like absolute crap. Though my maintenance calorie intake is upwards to 2,850 and I only eat 1.4K calories if I don’t snack or eat a third meal but if I snack probably more near 1.7k and a third meal ether 1.9k or 1.6k depending on which meal I eat again. Though these are Peanut butter grilled sandwiches and frozen party pizzas. Everyone I know questions how I’m still alive. So any help her would be appreciated! Thank you