I'm 13 and 83 pounds?

I do eat a lot of junk food not much vegetables. I don't take sports don't have any medications or infections nothing towards my health. Absolutely nothing so I am pretty healthy just I don't eat much healthy food. I eat 3 times a day and sometimes skip lunch and when school was here I skipped breakfast everyday but had lunch and dinner and unhealthy snacks. 83 pounds!!!! Please help