I had exactly the same problem when making my flashcards, but what worked for me was to make one flashcard for each lesson. I made mine mostly once I'd finished each unit. On one side was the specific topic/lesson title, and on the other the notes, strategies or formulae depending on the lesson. Here's an example from the straight line topic, which you've probably done as it's Unit 1: SIDE 1: Collinearity SIDE 2: [Points which lie on the same line are collinear]
If gradients are the same, points are collinear
State: 'points are collinear as Mab = Mbc with B as a common point'
I colour-coded cards into the three units, then wrote in the corner of the front of each card the topic. If you're finding it hard to word the cards, try using the notes from your teacher or the HSN notes. However, if you don't understand what they mean, ask your teacher to explain it in easier terms. For me, what was most important was to have a quick summary of definitions and strategies, so I could apply them to any question. Hope this helps! 🙂