Student or Learner
1. You read three books!
2. You bought a dog!
3. You wrote a book!
4. You ran six miles!
Are these exclamations or interjections? As far as I know interjections are only short words like: Wow!, Hi!, etc... These are much longer.
I would only all them exclamations if, in the context they are spoken/written, they actually act as exclamations. Otherwise, they are simply statements.
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.