Congrats on finishing up, glad to hear you enjoyed your work, that’s always a good sign. Mixing projects and study is a great way actually practice what you’re learning and, as you seem to have noticed, give you a little more motivation to continue learning.
It’s perfectly reasonable to look back and improve on an old project when you’ve learned something that could improve it and running through online resources whist you work is just par for the course .
For a bit of feedback-
It may be worthwhile spending a little more time to introduce your dataset. Imagine you were looking at this without prior knowledge; would you be able to understand what was being analysed, and why, in the first few sentences? When presenting an analysis like this always consider how your viewer would interpret it; try to make it is as easy as possible for them to understand.
I also think this work would be greatly improved if you could further your analysis to draw some conclusions from the data, see the original portfolio project details if you wanted some ideas. Your addition of a model to try and predict the insurance costs for an individual is interesting and worthy of discussion so perhaps add some in. Details and inference about how well the model predicts the data, do different variables affect the model more, are there any flaws or potential improvements to be made would add a lot to this work.
You’ve done the analysis, now you just need to let your viewer know what you found.