My 2 year old daughter is a very picky eater HELP?

Hello my daughter is 29 months and weighs 25 pounds and is a very picky eater. Some days she will eat great and then other days she wont eat at all. Her menu consists of scrambled eggs cereal chicken nuggets macoroni and cheese spagetti sloppy joe sauce pizza mash potatoes corn chips and cookies. THAT’S BASICALLY IT. I give her 1-2 Pediasure shakes a day to make up for any missed nutrients. I also try introducing her to new foods without any success. All she does is cry and throw a fit. Her doctor says she is perfectly healthy and that her weight is fine but as a mother I still seem to worry. How can I go about in introducing her to new foods and what else can I give her a vitamin supplement to make up for missed nutrients. Any advice would sure help. Thanks.