Yes! This, a thousand times this...
You're doing some brilliant things here, Sarah - laughing at yourself for mistakes, turning it into a game kind of approach - this are very consistently the things we see in our very best learners, so you're very much on the right road there.
Now, this thing about forgetting earlier vocabulary - I think you've fallen victim to a common misperception about learning, which the school system helps spread...
Memory isn't on/off.
Memory works on something much more like a very long sliding scale.
It seems like a picky detail, but it's really, really important.
On/Off means if you do a test and get 15/20, you haven't learnt those other 5, and you need to go and revise them. It's easy to see why schools end up strengthening this misperception.
On/Off means when you get some new words, and lose control of some older words, you think you've 'forgotten' them, and that you need to go back and revisit those lessons again.
But here's what's really happening:
Memory gets put down in layers.
No word is a single item - they are a highly detailed mash-up of phonemes and syllables that we retain partially. The first time you hear a word, you might only 'remember' that it starts with a particular letter, or that it's quite long - and then each time you hear it again, your brain will encode a little bit more, until eventually you have the whole word encoded - but even then, you might not have produced it often enough for the elements of production to be working smoothly - so you go through a stage of recognising it but not being able to say it (and call that 'not being able to remember it' too!).
So when you think you've 'forgotten' a word - that isn't what's happened.
Technically speaking, I mean, at the synaptic level.
If you've ever produced a word, you have the vast majority of the structure of that memory in place - when they blink in and out of being accessible for you, all that means is that you need a very little extra exposure.
Here's the thing - you'll get that exposure in subsequent lessons - we revisit EVERYTHING on a very deliberate pattern, precisely because of this.
So the next time you feel that you have 'forgotten' a word - instead of repeating sessions, try trusting the sysem, and moving on to the next lesson.
You might find your entirely approach to language learning changes if you decide to do 10 lessons in a row with repeating any of them...