I got my MacBook Pro on the 1st of September and I'm a bit worried about the battery life. At the moment the screen brightness is one bar and bluetooth is off, which is how I normally have it and the battery life time estimate keeps changing quite a lot. 5 minutes ago it said 5:11 left, and since then it's changed to 7:30, 7:58 and now it's saying 6:50 and is now on 95% and 8:03. I'm not doing anything differently and I don't know why it's doing this. Can anyone help please?