Welcome to the forum Debbie 
You’re not alone in struggling to remember the sentences - it’s perfectly normal because it’s a method of learning we’re not used to. Stick with it though, it does work - you don’t have to be able to repeat everything perfectly in order to move on.
It’s best not to write notes if you can avoid it as it detracts from the way the method works and actually slows the learning process.
The dots are all explained here: Pink, red, green, blue and beyond... what do they mean?
The later lessons are along the same pattern but they do get longer and harder - no point sticking to first gear for the whole journey! Subscribing (depending whether you subscribe to one of the structured courses or just go through the levels at your own pace) can also offer extra exercises and support.