If you use cleanup software like CCleaner then check the settings for the Firefox application.

CCleaner is run manually so it wont clear the history till I tell it to

For anyone else having this issue this is how I fixed it.

Check this: places.history.expiration.transient_current_max_pages mine was set to 400 for some reason

Change this: places.history.expiration.max_pages increasing that value will allow you to keep more or less pages in your history. I now have mine set a 1000.