Past tense of catch is caught. You can rephrase the second sentence to be more concise. Example: Some of the grammar points that I didn't get at the time I wrote them, I now understand why they were wrong and the mistakes I made.

“Noticed” works slightly better, but your text is pretty much correct! How’s your spoken English? If you’d like to go over your exercises on a regular basis or just have some chats about topics of your choice, in order to improve your English, send me a message!