Am I malnurished?Do you think I eat well?

For the past Month Ive been eating all kinds of things(since I have no cullinary skills besides frying an egg) and I sometimes feel dizzy or at times my heart races fast.I am 21 year old slim guy who goes to the gym at least once a week I try to gain weight but its hard.Usually after I hit the gym I go to boston market get a plate of white chicken macroni and cheese with some collard greens(doctor says I have low iron) and potato.That is what i eat after I workout which is usually twice a week or once a week.Weekdays before I go to work I have egg and bacon sandwich ,then some pizza.In the evening I have some mexican food which is like a burrito or a quesadilla(I work at a mexican restaurant).Then I have another big meal right before bed like at 11:00 right after work which is like chinese food (chicken brocilli and white rice).Recently to save my budget Ive been eating alot of mcdonalds chicken sandwiches and pizza .Its cheap and fast. But I havent been feeling right .Do you think Im eating right?