Is it normal to feel like I don't know anything?

Hi Ajay! First of all I do not believe you do not know anything. Engineering can be a really broad career, and in school they throw at you as much information as they can. What you need to understand is that school is giving you a taste of all the possible paths you can take when you graduate in terms of specialization.

So lets talk about the classes. All basic classes like Math, Physics, Chemistry, etc, are necessary for you to have a base and understand the career classes, but in reality you will not be using all of that all the time, there are tools that will do the work for you, but again you need to know the basics to understand if the results you are getting from tools make sense or not. Do not think you need to remember every formula by memory, I am constantly going back and reviewing my books and old notes when I need to, and of course Google is always your best friend.

Regarding career classes, again school will give you a taste of all fields in the major you have selected. Sometimes is hard to see the point of the subjects if professors do not give industry examples, or teach you the class with an application point of view. However, you can always take some time and dig deeper yourself. Books do not always explain things easily, but these days the internet is full of great resources and people that take time to make videos and explain things better and easier. I know it can be hard to find more time when you are full of things, but it is necessary to look at things from different perspectives to fully understand.

Also, remember that "practice makes perfect". While you focus more on a particular subject you will get better at it every day, and this is what happens at work. In the industry you will have a particular task and you will be fully dedicated to it. Make sure you research about the types of work you can get in your particular field and select something that you really enjoy. Think about what is your favorite class. Try to get internships, this is a great way to have a taste of the industry and you will find experienced engineers that can guide you and show you how things work in the industry, which is really different than how they work in school. Many times school is harder as professors want you to learn and will push you to do things the hard way. 

Tell yourself that you are very knowledgeable, do not feel you do not know anything because that will not help you. It is totally normal to feel this way because school can be overwhelming. However, do not let this to affect your day to day life. Think that you just need to find a different perspective to understand things better. If you are struggling with a class seek for help, try to find a good study group where you can collaborate with others. If not, just go to YouTube and search for videos about that class, believe me you will find someone that will make you understand.    

Remember school is not the same as the industry, everybody started not knowing anything and that is why you go to school, to learn. 

Hope this helps!