Well, it's a very unorganized mess when I try to come up with a character, but I'll try to help best I can ^^
I begin with the world, because the world that surrounds them really shapes who your character is going to be, ie, if the surrounding world is cyberpunk post apocalyptic chaos, then a character will very well be affected by it, making him or her less trusting or more resourceful. Two minutes of this thinking can get a whole list of traits.
You can also take it a step further, and think about how your character responds to their environment due to the conditions. Going back to the cyber punk, he or she is a loner because they don't trust anyone. The loneliness could regress and make them cold and unfeeling, or it could explode, and leave them a psychotic husk of a human being.
So you have a vague representation for what your character will be due to her experiences in the world your role play is set in. In this case, a lone-wolf scavenger cyberpunk. After this is usually when I come up with the personal story of the character. Instead of thinking about how the world functions around them, think of how they experience the world around them, and slowly build a cohesive background.
In our scenario, we have our cyberpunk, born of a middle class family. After a certain few nations get their hands on highly advanced mysterious tech, there is a massive global conflict on how it's to be used and distributed. One nation threatens another with the tech on their side, and a trigger happy executive fires a nuclear bomb, triggering a chain reaction of mutually assured destruction, and decimating the world with radiation. However, fortunately for our protagonist, she was on a field trip away from her hometown, which was ground zero for an explosion. Weak from radiation and desperately homesick, our protagonist slowly learns the hard way that life isn't all cupcakes and rainbows. Betrayals, stealing, lying, and killing filled her life, blah blah, generic apoc stuff.
Now is the point where I flesh out the details, and build a better, more cohesive plot line, and define my character's appearance, which can change dynamically with how your character develops. Things like appearance, likes, dislikes, favorites, I all figure out here. It's especially easy if I'm already thinking of what the character will be doing. It comes to you more naturally in a sense. Going back to the epiphany where life isn't 'cupcakes and rainbows', she could strongly dislike these things due to the fact that her childhood was taken from her in such a violent and destructive manner, leaving her bitter at the reminder of what could have been. On the other hand, she could like these things, knowing that while the world is crumbling, there were, and will still be, rays of sunshine, triggering feelings of nostalgia.
(Yes, I may be influenced by other stories, and this is just a character I rattled off, sorry if it seems a bit generic.)
I hope this helps dood. Near the beginning, I mentioned how messy my style is. I said that because while I had an order of how I make a character, I often jump back to other steps in light of new or better plot points, replacing old, clashing timelines and plot points with a smoother story that makes more sense.
And whether or not it's 'too much', it all depends on how much you want to give on your character. I never reveal everything initially in a role play, or even just writing. You just play it by ear, and you'll do fine.