Each time, I have no traction

Are you sure? How are you measuring that? How much traction did you need? Need to accomplish what next step? Are you trying to bootstrap from 0 -> profitability without taking funding? Are you looking "just enough traction to get funded", or "other"?

"negative feedback"

What kind of negative feedback, and how did you react to it? There's a difference between "this is a really stupid idea and you suck" and "this could be useful, but not until you add a FR$OZGIBIT interface".

If the feedback helps steer you in the direction of a better product, better product/market fit, etc., then it's actually a good thing.

I demotivating and then I stop the project.

Why did you stop? Did you have a concrete idea, going in, of what goals you were trying to accomplish, what metrics you would measure, and what your "success criteria" would be?

I read too much about pretotyping, MVP, lean startup, marketing

Hmmm... all of those things, in isolation, are potentially very valuable. I'm guessing you mean something like "I read all this stuff and saw conflicting advice" or "I read all this stuff and was drowning in information and couldn't find a cohesive narrative to link it all together" or "I spend too much time reading this stuff instead of actually building my $FOO".

In any case, I can only share what I've found valuable. Read Steve Blank's The Four Steps To The Epiphany and/or The Startup Owner's Manual. Steve's work gives you something closer to a "paint by numbers" approach than anything else out there. The Customer Development approach gives you a process to follow, so - at least - you won't just be drifting around doing random stuff because you read about it on a blog link from HN. Start with CD and then add in other "stuff" as you work through the process.

Guy Kawasaki's The Art of the Start is also an excellent read.

Now I don't even know what to do.

Well, you could give up, feel sorry for yourself, mentally berate yourself for not accomplishing more, maybe drink a lot, or take up a cocaine / heroin / crystal meth habit, or just spend all your time getting stoned and listening to Pink Floyd.

You could watch Glengarry Glen Ross about 100 times, and take the famous "sales speech" scene way to literally, get really fired up and charge full-bore into a new initiative, planning to kick the world's ass.

You could sit back, take stock of where you are, what resources you have, and what your passions are, think about where you want to go, and meticulously put together a plan to get from "point A" to "point B".

It's really up to you. No options are ever really off the table.

All ideas I have seems already made by someone else, and often better than I planned to do them

One: seems is the key word here. It's probably not literally true that you have no novel ideas at all. Two, it doesn't matter, as even IF you do have a novel idea, it won't stay novel long. There are too many people in the world... what ever idea you thought of, somebody else will have the same idea if they haven't yet. Who cares? Do it anyway, and out execute them.

Bob Parsons (of GoDaddy fame) once said something roughly like "Don't be afraid to enter a crowded market, just be better than everybody else".

Another way of looking at it... if you are working on an idea that nobody else is working on, it's either something really amazingly new that you've invented (congrats!) or it's a really stupid idea. If other people are working on the same thing, however, that is a measure of validation that the idea may, indeed, be sound. Now go out execute those scumbags... they are trying to take your lunch money!

Each partners I meet seems too newbie to work with

Fine, forget partners for now.

I think all those failures killed me and now I'm lost. What a waste.

http://www.youtube.com/watch?v=KQQcOQsCFnw