Erin,
First, I would say NO it is not rigged or fixed against you. Like others have said, you should NOT auto battle for a long time.
Personally, I have a pretty high attack boost on my primary world, +148% to be exact and I lose troops all the time too.
What matters most is that you know what you are fighting against. The computer has a way of going after certain troops first, then others.
There are multiple guides that will help you see what is best for which age. In my primary world, we have a GvG Tutorial and multiple videos to help people fight better. They are easy to find if you go to youtube and type in, "how to fight in FOE". You will find many videos to explain many things. But this is the best advice I can give you, look at the map and what troops you are fighting against. You must always try to use plan ahead, there are many reasons why it shows the order of battle on the bottom. I will not give away everything I have learned or know, I am not the best fighter, I am pretty solid. I have found I can take very low damage to no losses at all, when I fight it my way and look ahead. Get some Rogue Hideouts and look at how to fight with rogues too. There are two ways I fight with them. But again, this is all part of the game and once you get the hang of it, you will fully understand why and how the computer fights against you. It will then because easy for you to look and plan ahead. For now, you have a learning curve and right now, DO NOT USE Unattached troops to fight with, until you get better at fighting.
Spend a few minutes watching a few videos and you will learn a lot of tricks, I promise.
Steve - LordStevie