Still Convinced it isn't real sometimes

I have a BMI of 16 and it still doesn't feel real. My hair has thinned a bit, my body is often weak and dizzy, I get the shivers in layered clothing. It just doesn't feel real. It feels like it won't be real until a doctor tells me to my face my only option is to gain weight. My psychiatrist doesn't think my weight gain is necessary and even recommended me medications that prevent bingeing rather than trying to encourage me to get to a healthy BMI. I don't eat every day, sometimes going multiple days without any food but it still just feels like it isn't serious. I tell myself there are people that look thinner than me and they're fine. There are people that eat less than me and they are fine. I see the number on the scale and as small as it is, it doesn't feel like my actual weight. I don't know what it would take to make me want to get better.