Sometimes I have felt that Euphoric feeling and sometimes I don't so I think that it could be person specific. Being able to feel your eyes moving back and forth could be a form of Sleep Paralysis, you could be imagining it, but I am guessing it's the first of the two.

As for what you are doing wrong to become completely lucid it takes some practice to be able to become completely lucid. In my opinion you can just pick up Lucid Dreaming your first time and become a master so dont worry to much about it.

Some tips I found to have worked a few years ago were Reality Checks where if you think you might be dreaming check for some things that are obvious clues for instance time. If you were to look at a clock in a dream it would read a time, and then if you were to look back at it again it would be a different time. Now a way to incorporate this into your real life and your dreams is to check the clock quite often so it becomes a habit (you could get a watch). Now that you have done that you may find yourself checking your watch or clock in your dreams and noticing the time being different therefore signaling that you are having a dream.

There are many different methods which you can find on the forums you just have to find what works for you. As for staying lucid or becoming more lucid once you are lucid Rubbing Your Hands Together really fast and Spinning Around in circles can do wonders, the times in which I have remembered to do this has caused the dream to become much more vivid and lucid as well.