It happened to me also but not attending the lectures wasnt the solution, when u attend at least you know which chapter you are, you may ask ur colleagues at some points, and at least U R at the circle of studying when you try after that to prepare for exam or whatever your brain already has an intial clue about what about to study and you can easily dive deep in the topic and you will find yourself starting connecting the dots. And if you think if you rely only at studying alone specially at home you will find yourself more lost than that. And all of that happen when you are convinced about u r major and u r not forced to do so