I love my Eagles, but, as many others have stated, they are not meant to be straight discs. Then again, neither are the Avenger SS or Sidewinder. Both the A-SS and SW are very, very understable. Typically, to get these discs to fly straight, they are either hyzerflipped on a pretty extreme hyzer, or they are underthrown drastically. I by no means intend to insult you, but if you're only a few months into the sport, I would gather that your form and arm speed are not ejecting the discs at proper speed. Meaning that for higher speed discs (Sidewinder: 9, Avenger SS: 10) you are relying on extremely understable discs to fly straight, instead of turning as they are intended.
A good judge of why the Eagle is behaving this way would be to measure how far these three discs are flying for you. They should all be going a minimum of 300' on a flat release to see the projected flight paths. If you are throwing much shorter than that, the flight rating numbers will be heavily skewed. In that case, I would recommend slower discs and working on form (tons of resources for that from blogs, to youtube, to posting form critique videos for others to offer help)
All in all, an Eagle should be quite overstable. Especially in Champion plastic. My Star Eagles fly very true to flight numbers with a little turn before hyzering out, but in Champion plastic at max weight, they fly very straight for about 280' before a fairly strong fade and big skip, ending around 320'. When I do an alt bag, I use these as mini-PDs.