It would probably be helpful to start at a level above where you left off and look up specific gaps in your knowledge as you find them. It’s always good to come to a topic with the understanding of every previous topic, but often those deeper understandings come from moving into more advanced subjects anyway. It might be more slow and frustrating at times, but it will give you a better understanding of where your specific gaps in knowledge actually lie and you’ll be able to address them as you go.