Not doing so great at algebra 2?

My mother asked me to teach myself algebra 2... I am not doing so well. I may fail the course. Because of endless procrastination my mom believes it it because i am lazy that i am not going through it. However i make my current geometry teacher lecture me for 3 hours after school every week. I took my book to a Friend. He said that the book is a collage algebra 2 book. I do not understand this course. I am getting a c. this will ruin my gpa. if ido not understand algebra 2... how will i understand higher maths whenever i go to collage? I plan to be a vet. It is a major science degree pretty much, and this math goes with it.