Some people like to be treated badly. Jeffrey Dahmer felt he was acting in his enlightened self interest by killing and eating his sex partners. So no, your morality is just subjective preference. Both you and Dahmer base your decisions on your feelings and understanding of self interest but just produce different actions. My ability to address the dilemma is irrelevant to the fact I have an objectively rational basis for my morality. The objectively existing moral character of God is the basis of my morality. Euthryphros Dilemma does nothing to refute that fact.
A morality that has a rationally objective basis is the exact opposite of morally bankrupt and illogical. See above why your morality is both of those exact things. You have no objective definitions of like, badly, or self interest. Or even empathy.
First, we have now established that you do not have a functioning system of morality. Oh, no doubt you're a nice person who lives as virtuous a life as anybody, but the reasons you give for your system of morality simply fall apart when analysed. Euthyphro's Dilemma shows how a moral system based solely on the character of a deity is completely meaningless. You may not accept this, but since all your arguments to the contrary are nothing more than denial, it's plain for anyone else to see.
A system built on enlightened self-interest does not mean "do anything you want at any time, with no concern for how it hurts other people." Try it if you like, and see how it works out! You'll find that, in general, it is not in your own best interests to be a horrible person. The people around you react to it and make life difficult for you. It's in your own interests to be good to others so they will be good to you.
Jeffrey Dahmer is actually a really good example of how morality works. If morality is about doing good to others because it's good for you, then Jeffrey Dahmer acted immorally. And what happened to him? He ended up in prison, and came to a very nasty end. Of course, it's quite possible to imagine a person who does devote a life to hurting other people and doesn't suffer any ill consequences, but that doesn't invalidate the system. Quite simply, when you act immorally, increase the chances that the trouble you are spreading in the world will, sooner or later, come back to cause you trouble.
It's perfectly possible to construct a system of morality based on human nature. We don't want pain; we do want happiness. That's what it means to be human. Of course, what causes us pain or happiness varies extremely widely, but that's just a detail to be worked out. It may be a complicated matter to work out, but morality can be complicated sometimes.
Do you have any more objections to a secular system of morality?