IIT Preparation

I will suggest you to first strengthen your fundamentals as it is very important for your class 11th and 12th board and very well needed for the IIT exam. IIT exam is not a rocket science, you just need to be more dedicated to proper time management as you have to balance your 11th with IIT preparations.
For example, if you read Kinematics, I will suggest you to make your fundamentals strong with a standard book or any other means with which you feel comfortable then solve your class 11th questions first and analyze yourself and then refer to the previous year question papers of IIT and try to solve them as well and analyze your solving skills and time management.Just remember, to achieve something different, you have to do things little different.
I hope that this will help you to decide what to do, and if you have any doubt, feel free to ask.
All the very best for your future!

Smart practice is the key to crack IIT examination. Don't forget that cracking IIT exam is tough and you need to score 300+ marks. This is impossible without smart practice. Let me share some of the personal tips and tricks that I followed to get into IIT which may also help you.
1. Understand what works best for you
You need to understand what is the best schedule "you can follow" and not the one you force on yourself. Find out the best time that suits you or which place in the house you are comfortable in. The more concentrated you are when you study, better will be your preparation. It may sound silly to some, but this has helped me prepare faster and better.
2. Work on your weak areas
Everyone has a strong subject which they understand easily and can solve questions correctly without worry. The problem is with the weak areas. I myself was not good in chemistry subject. Then, I started working on it more and made it the primary focus of my studies. Within no time, I could easily convert it into one of my strong suits. So, make your study timetable that you are comfortable with and allocate more time to weak topics.
3. Practice as much as possible
Practice is the backbone of your path to rank in IIT. It is the most crucial element. Most of the students today focus only on studying i.e. reading the chapters and reading the illustrations and scribbling on the pages saying that they practice. When the real exam happens, these students say The paper was very difficult or they did not get much time.
For example, a pilot cannot learn to fly by reading the books. They spend a lot of time practising. Practice is the most important point that you need to focus on in case you are really serious about cracking the IIT examination. For practice, I personally used the CareerOrbits IIT-JEE course and would recommend the same to you too. Their questions from the CareerOrbits courses are far better than the branded institutes and cannot match their quality.
4. Revise repeatedly all the incorrect attempted questions
Always revise each and every incorrectly attempted question repeatedly. If you miss this, you do not get the rank you want. By practising repeatedly, your brain automatically grasps the concept and after a certain point, you can solve questions with ease. And yes, it was easy to do so for me since the JEE Advanced course from CareerOrbits tracked all the questions that I attempted wrongly and compiled 3 revision lists for me.

English Phobia is mostly in our heads. There are no grounds for the poor performance in English. Rather, India is 4th out of 19 Asian countries in term of English proficiency.
Don't be disheartened by criticism. Work hard on academics and speaking English. You'd be surprised by the results.
Firstly, start reading English newspaper. I suggest this step to everyone I come across. This not only improves your vocabulary but also gives you a sense of being better informed. http://carryongarry.com/learn-500-big-english-words/
English will not obstruct your JEE journey. It is part of the syllabus in boards and learning language is as important as being well versed in technology or PCM subjects. But ultimately in JEE only PCM is going to get you scores and marks.
For improved English, your last step can be enrolling for a coaching. There are various Personality development coachings that work on your language and communication skills too.
It is a fun activity and I would suggest it only if you want to join one. You'd come across many people like you who are struggling with their English.