Solved: Re: InDesign Fonts Looking Different Sizes

I'm trying to format a short story on InDesign. I followed this tutorial.

Lay Out a Print Book's Pages with InDesign CC 2017 - YouTube

Everything worked really well. The only issue I have now is, no matter what size I change my font to, different words look completely different sizes. I don't know if it has to do with the text being justified left? And it's an attempt to keep more words on certain lines?

Anyway, it looks really unprofessional as it is. The text was originally all 12pt and is now 15pt. Exactly the same issue either way.

I haven't found anyone else saying they've had the same issue. I have read issues with text looking different thickness on different pages and apparently that can be to do with images and transparency? As I only started using the program yesterday, I don't really understand this very well. However, I only have one image on the first page and it's a jpeg. I tried deleting it and I still had the issue.